I have been working with, Mate, Cinnamon, Gnome Shell and Unity. I have used all of these desktop environments for about a week to compare them. The winner for me was Cinnamon. The 64 bit main edition with Cinnamon made the best use of desktop effects, it is easy to change themes and has a high level of functionality compared to the other environments. The menu used in Cinnamon really has a nice modern look to it and I especially like how it can be made semi-transparent.
Cinnamon has the familiarity of the Gnome 2x desktop but it still uses the hot spots on the screen the way that Gnome Shell does The desktop effects used seemed ideal to me, just the right amount of bling but not overdone. The default effects make the system very pleasant to use without getting in the way.
I like Unity but the current method of minimizing windows is kind of clunky because of the tiny buttons that are used in the taskbar. Cinnamon has the show desktop feature and the familiar panel features that make minimizing a window very easy. Gnome Shell on the other hand, trevolves around the use of multiple desktops. Gnome Shell seemed difficult to change themes, Cinnamon came with a nice selection of themed and it was easy to get the look I wanted for the desktop.
Breakage from updates was something I kept in mind too. I have had minor breakage from updates with Unity. I have had the , system error I saw in the beta releases return after applying updates, this has not happened with Cinnamon. Cinnamon has held up very well when the system is updated. Gnome Shell and Mate both held up well with updates too. I like Mate but Cinnamon has desktop effects out of the box and compositing seems to be more geared for the newer desktop environments. It was nice seeing the Mint menu in Mate but the menu used in Cinnamon just seemed more visually appealing to me, just personal preference on my part.
Memory use was about the same with all of the desktop environments I tried, they all were pretty resource friendly for being 64 bit releases. Gnome Shell seemed a little slower than the rest for launching applications, it was not bad but it was noticeably slower than the other environments. Mate seemed to be the quickest at launching applications.
I like how Clem stuck with using a black plymouth screen, plymouth just does not work well enough in Ubuntu or anything Ubuntu based and I would rather see the black screen at start up rather than a messed up looking plymouth theme.
Cinnamon and Mate both seemed more complete compared to Unity and Gnome Shell. I do have Fedora 17 with Gnome Shell installed on my laptop because it is easier to see on a smaller screen and until my eye heals I need the Zoom feature it has to be able to read some print. Fedora did a good job with Gnome Shell but I did have to install the extension to have shutdown and re-start appear in the menu. Installing codecs in Fedora was painless with the script tool that was available. Changing themes in Fedora seemed challenging, for now I will just stick with the default theme.
The Mint 64 bit main edition was the best choice for my main computer because it has a good balance of features and usability. Cinnamon is a nice blend of the old and the new and it demonstrates what can be done with the newer versions of Gnome. I expect that there will be improvements made over time to all the newer desktop environments but for now Cinnamon seems to be more complete as far as features and usability go. I plan on keeping an LTS release on my main computer, 5 years of support is pretty hard to beat. For everyday use, Cinnamon seems to get the job done and I do not feel like I am missing anything.