I have been loving Ubuntu 12.04
12.04 was released a few months ago but I just got around to upgrading my Toshiba U505 yesterday. I must say that I don't understand some of the negative comments about Unity that I have read. Unity feels intuitive and so far has just worked for everything I have tried. A minute of google'ing found directions for seting up desktop files in .local/share/applications/. For an example, here is my .local/share/applications/rubymine.desktop file:
[Desktop Entry] Version=1.0 Type=Application Terminal=false Exec=/home/rubymine/bin/rubymine.sh Name=RubyMine Icon=/home/rubymine/bin/RMlogo.svgObviously change file names and paths as required for your apps and your system. Then anytime when I need to run RubyMine I tap the ALT key and the Unity search bar appears; I start typing the first few letters of RubyMine and when the icon pops up I just click it. I also set up IntelliJ this way for Clojure and Java development. I prefer this to creating task bar icons. Very similar to using Command-space on OS X.
The only disappointment (so far) is the lack of an officially supported Evernote client for Linux. I appreciate the work the developers put into the open source client NixNote, but it lacks polish. Still, I am glad to have it!
I was very pleasantly surprised at how well the Dropbox Linux client works. Once it synchronized my files the service uses little memory and CPU time and everything is well integrated with Unity.
I have been pretty much using OS X Mountain Lion (dev preview, now the gold master) for my work this year but despite the lack of general polish in Desktop Linux there are some real wins in using Linux, at least for my workflow because I can match my development environment on my laptop with my servers, and some small time sinks of dealing with OS X go away. Since my tools like IntelliJ (for Clojure and Java), RubyMine (Ruby), Emacs, Dropbox, and lots of git repositories all work the same, it is really pretty painless for me to enjoy using Linux for a few days, alternate back to OS X, and choose the dev environment based on what I am working on.