MG Seigler from TechCrunch gives us the low down on OSX 10.8 Mountain Lion..
But ending my review there wouldn’t do Mountain Lion the justice it 
deserves. It’s definitely the most polished and robust version of OS X 
yet. If you liked Lion, you’ll love Mountain Lion. If you didn’t like 
Lion, you’ll probably love Mountain Lion even more because it seems to 
fix a lot of the performance/quirkiness issues that some folks were 
having with the last version of OS X.
I didn’t have any of those issues with Lion, so as someone who had 
started using an iOS device far more than a Mac, I liked Lion right from
 the start because it borrowed a lot of little ideas from iOS. And 
Mountain Lion expands upon that practice. So, unsurprisingly, I like it 
even more.
It must be said that Mountain Lion isn’t really all that different 
from Lion — hence, the variation of the name (even though mountain lions
 are technically cougars — insert joke here).
 But unlike the jump from Leopard to Snow Leopard, which focused on 
performance and tightening code rather than features, the jump from Lion
 to Mountain Lion does pack some new goodies.
Apple has already highlighted what they view to be the 10 key 
features of Mountain Lion, both in the original previews and at WWDC 
last month. I won’t spend time giving an overview of each of them again —
 if you’d like that, go here.
Instead, I thought I’d talk a bit about my experience using Mountain 
Lion over these past several months. And point out the things I like the
 best, and a few things that I don’t like.
Initially, I just had Mountain Lion installed on the review machine 
that Apple loaned me back in February. But as Mountain Lion quickly 
became more stable, I decided to install a developer build on one of my 
personal Macs as well. On a mid-2011 MacBook Air, there were no 
noticeable performance gains (nor is Apple touting any), but the machine
 did seem to wake up much quicker from sleep. More recently, when I 
installed Mountain Lion on my 2009 iMac, I did notice that my machine 
started up (and shut down) significantly faster, which was nice. 
Overall, that older machine has had no issues with Mountain Lion (though
 there are limits as to just how old a machine can be and still run the new OS).
App compatibility has been surprisingly good. I actually haven’t 
found any with major problems due to the upgrade from Lion to Mountain 
Lion. I’m sure there are some out there, but even apps that pushed out 
Mountain Lion-ready updates a little early seemed to work fine without 
the updates (the updates just added things such as Notification Center 
capabilities).
Notifications are the most in-your-face and probably best new feature
 of Mountain Lion. We’re all used to dozens of apps on our machines 
alerting us to something. Now the process is streamlined in a very 
iOS-like manner. While there aren’t too many third-party apps out there 
that support these new notifications yet, Apple’s built-in apps alone 
make this a most-welcome addition.
Those built-in apps now include Twitter in Mountain Lion. If you sign
 in (from the settings) with your Twitter account, you can now get 
notifications every time someone @replies you or DMs you. It’s 
fantastic. And while there is a button that enables you to tweet right 
from the notification area on the right side of the screen, when you 
reply to Twitter notifications, unfortunately you’re dumped into the web
 app (who knows what Twitter is doing with Twitter for Mac, which still 
has the old Twitter logo and non-Retina graphics).
Also built-in will be Facebook. Oddly though, this feature won’t go 
live until the fall (with an update to Mountain Lion). Apple gave me a 
build with Facebook enabled, and it seems to work well. You can post 
with the click of a button just as you can with Twitter — and it works 
with Facebook’s more granular sharing settings (share with just your 
family group, for example). I assume Apple wants to give developers a 
little more time to work with this Facebook integration, as many of them
 will want to use it for things like Single Sign On for apps, and 
sharing.
The fact that Chrome and Safari work with Notification Center is 
great news for web apps. I’ve been able to get alerts when I have a new 
Gmail message, for example. Chrome has had a similar banner system for 
some time, but the native OS X notification experience easily blows it 
away.
Another feature that users are likely to notice pretty quickly is 
Gatekeeper. That’s a bit odd since it’s not really meant to be a 
forward-facing feature, but rather it’s meant to be more of a protection
 layer. But since the default setting is to block unsigned apps from the
 web, people are likely to hit it right away (since most developers 
won’t be properly signed at the launch of the OS). Don’t panic. This 
doesn’t mean you can’t install all of your favorite apps via the web 
with Mountain Lion, it just means that you’ll have to go into settings 
and hit a button to allow for unsigned app installs.
I suspect we’ll see a little backlash against this early on simply 
because there won’t be a lot of developers signed up just yet. (And I 
can’t wait to watch parents try to figure out how to change the default 
settings.) I’m told some bigger ones, like Adobe, are already on board. 
But there are thousands upon thousands of developers out there that will
 want to get the certification (which only requires a $99/year developer
 account — there’s no vetting at first, it’s an honor system until you 
do something wrong). It may take a little time.
Another new feature that I’ve run into time and time again in 
Mountain Lion is Documents in the Cloud. Because iCloud is now fully 
baked into the OS, you’ll find this feature as a part of everything from
 TextEdit to Preview. This also may be a bit jarring at first because 
it’s really blowing up the traditional notion of a file system, at least
 from a conceptual perspective. Rather than files residing in folders on
 some drive that you access through Finder, files are now simply 
documents within the apps themselves.
That probably sounds more confusing that it is. It actually makes a 
lot more sense to do things this way — and again, it’s something 
borrowed from iOS. When you open a document-based app in Mountain Lion, 
you’ll be asked to pick which document you wish to open from a list of 
documents specifically tied to that app. If you want to open an outside 
document, you still can, but it’s a step away now into the folder 
system.
Then there are the apps that have been ported over from iOS: 
Reminders, Notes, and Messages. Each is great provided you’re also an 
iOS (and by extension, iCloud) user, otherwise they may seem 
weak. Messages was released in beta form late last year as a replacement
 for iChat. It’s probably good that Apple did this because it was very 
wonky at first. In Mountain Lion, it seems much more stable. More 
importantly, messages delivery seems to actually work all the time now 
no matter which device you’re using.
But for people who were used to iChat, with its more traditional IM 
ways, Messages will probably seem a bit odd. Even now, the iMessage/IM 
duality is sort of strange — am I supposed to close/delete messages 
after I’m done with “chat session”?
Another killer new feature of Mountain Lion that I find myself using 
quite a bit is AirPlay. iOS users will know this well, and they should 
be thrilled to have this for the Mac now. A couple weeks ago, there was a
 sporting event that was being streamed live on the web, but wasn’t 
available on the iPhone/iPad. With Mountain Lion, I simply opened a 
browser window, hit one button, and my entire desktop was sent to my TV 
via my Apple TV. I put the video fullscreen and you couldn’t even tell 
we were routing this, wirelessly, through a computer. Magic.
One feature I’m still not completely sold on yet is Safari. Apple’s 
web browser has been around for years now, and each year, Apple seems to
 claim it’s the fastest out there. The problem is that there are so many
 tests now tailored to different things, that it’s hard to know what 
matters. All I know is that in daily usage, Chrome still feels faster to me, so that’s what I use.
But Apple has once again overhauled Safari to make it competitive 
with Mountain Lion. A couple key features rely on iCloud: iCloud Tabs 
and Reading List. It’s definitely nice to see what tabs you have open on
 other Apple devices, but Reading List feels less compelling in a world 
of Instapaper and Pocket.
The biggest change you’ll find in Safari is the addition of a “Smart 
Search” bar — or an “omnibar”, to use Google’s parlance. That is, a 
unified top text bar that smartly handles both URLs and searches. Chrome
 has had this feature for a while, and it’s a welcome addition to Safari
 (though, oddly, it’s not a part of Mobile Safari).
Also new is the Safari Tab View. This allows you to zoom out of any 
page and get a quick look at the tabs you currently have open. It’s a 
nice effect, but it’s simply not that practical. I’d much rather see 
Safari add something like pinned tabs, to make the tab situation more 
manageable.
While I said that performance gains weren’t a concentrated focus for 
Mountain Lion, one area the OS X team did work on is smooth scrolling 
and hardware acceleration within Safari. The work shows.
Overall, Mountain Lion feels like the most natural step yet towards 
the convergence of iOS and OS X. While Apple says there are now over 66 
million OS X users, Apple sold nearly 50 million iOS devices just last quarter. It’s clear that OS X has to continue to creep closer to iOS simply because that’s what far more people know now.
It’s hard to imagine how Apple will further refine OS X from here. 
Maybe they don’t — maybe OS XI (OS 11?) is next. Or maybe Apple has one 
more big cat left in the bag (in terms of nicknames, there really only 
are a couple left). For now, Mountain Lion will stand atop the mountain.
 It’s solid, polished, and perhaps most importantly, cheap.
For $19.99 in the Mac App Store, you’ll be able to upgrade all your 
machines to Mountain Lion. You can upgrade both Lion machines and Snow 
Leopard machines, and they both cost the same price, which is great. If 
your machine is compatible, the upgrade is an absolute no-brainer.
In a time when Microsoft is just about to upend their entire OS with 
their biggest change (and bet) yet in Windows 8, Apple has taken a much 
more refined approach. Perhaps they take some criticism for this, or 
perhaps they’re just being savvy. OS X remains a great OS. And sprinkled
 with some of the best elements of iOS, it still feels pretty fresh. Not
 bad for an eleven-year-old big cat.
You can find OS X Mountain Lion in the Mac App Store here.