I have been using Mac OS X Lion for a little over a week now and have some thoughts on what is great and what is not. Most reviews have been positive but some particular sticking points have emerged.
Install
First off, the Mac App Store purchase and install went very smoothly. I was impressed with how easy the process was. My experience has all been with my 2010 11-inch MacBook Air with 1.4GHz Core 2 Duo, 4GB of memory, and 64GB SSD. This machine is not a powerhouse but does great for most basic tasks which mostly consist of surfing the web, writing email, writing, and lots of terminal work.
Performance
One of the major concerns with any new operating system release is performance. When Apple moved from 10.4 to 10.5 performance seemed to suffer but ever since then, each successive release seems to feature better performance. The 10.5 to 10.6 transition was a big step in the right direction. Now the 10.6 to 10.7 progression is equally impressive. I have found that performance for the large number of apps I typically run is better under Lion than under Snow Leopard.
Multi-Touch Gestures, Mission Control, Launchpad, and Resume
I am pretty impressed with the new Multi-Touch Gestures that makes moving between "desktops" and full screen apps a breeze. I am using the left and right three finger swipe constantly to switch between the primary apps I use. Mission Control is also interesting but I am not using it too frequently.
Launchpad is nice but I have not found a good reason to use it very much yet. Eventually I may transition to using it more but I have to organize all my apps first. Resume is also a nice feature, particularly for Safari. All the other browsers I use automatically bring whatever tabs were open back up when I re-launch them but Safari needed an extra step of selecting "Reopen All Windows from Last Session" in the History menu. All that is fixed by Resume.
Full-Screen Apps
Other than performance, the best feature of Lion is Full-Screen Apps. Although some consider them nothing more than a gimmick brought over from iOS, I find them extremely useful and a great way to work and have increased focus and fewer distractions. One thing I would like to see resolved is that when you use an app in full-screen mode, a second display will only show a "linen" background and nothing else. It would be nice to be able to use the second display for something other than a very large "linen" background.
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There are a few specific apps that I use constantly in full-screen mode. First off, I have almost completely stopped using Apple's Mail program in favor of Sparrow. Sparrow takes a conversation-style view similar to Gmail and applies it to your regular email. It is fantastic and the best email client I have ever used. It is the first full-screen app I launch.
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The second full-screen app I use is Socialite. Socialite has become my go-to app for monitoring Twitter and Facebook. It also supports Google Reader but I prefer another app for that purpose. Socialite is impressive and allows me to keep track of Twitter lists and mark Tweets "read" after I see them. In versions prior to 1.3.5, there were some performance issues that initially caused me to move to another appliactions for social media but version 1.3.6 has addressed all of my issues. All in all Socialite is a fantastic social media client and is the second full-screen app I launch.
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The third full-screen app I launch is Reeder, the best Google Reader client I have ever used. Until recently, I have been using NewsRack in both Mac and iOS versions but started looking for an alternative. At this time, NewRack does not support full-screen mode and it does not have the clean user interface that Reeder employs. Reeder in both its Mac and iOS version has become my essential feed client.
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The fourth and critical full-screen app I use constantly is iTerm (actually iTerm2). Although Apple's own Terminal does a pretty good job and I do find it to be very good. iTerm just adds some additional refinements that I really like. Try it out and see what you think.
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The last full-screen app I use all the time can actually be considered many apps in one. Fluid App allows you to take any web site and turn it into its own launchable app that can support full-screen mode with the $5 paid version. The free version is still excellent but lacks full-screen mode and some other additional features. I use Fluid-created apps constantly for things like my own My eBay app, an Instapaper app, a FaceBook app, and a Netflix app. Fluid App provides an excellent way to segment your browsing experience particularly with sites you visit often. This leaves it easy to check often-used sites without using Safari itself which leaves the browser ready for whatever other browsing needs to be done.
Conclusion
Overall, I think Lion is the best upgrade we have seen to Mac OS X in a long time. As always, there are some bugs that will be worked out. Overall, I can say my experience has been great and I look forward to continuing to use Lion and also working with Lion Server soon. Check back for additional thoughts as I continue using Lion.
You can purchase Mac OS X 10.7 Lion and Lion Server from the Mac App Store.