Fair warning, I am a huge fan of the Enlightenment desktop. The following items in this post are things I believe the Enlightenment desktop (and it's developers) are doing better than some of the other open source desktops.
Maintain Old Releases
People are always resistant to change and switching your desktop environment is a major change. When KDE and Gnome both had their last major releases they promptly dropped their previous releases like a bag of bricks. The Enlightenment 17 desktop, while still in development, has been stable and ready for use for a long time now. Even so they have team members that maintain their older E16 release. It is still used (and liked) by many and there are no plans to discontinue it any time soon.
A Focus on Speed and New Features
There is no doubting that all of our modern desktops have been progressing in features and functionality. One spot where Enlightenment excels though is that it has a focus on remaining trim and fast while adding these new features. Don't believe me? KDE 4.x needs around 512megs to be happy, Gnome 3 recommends slightly more at 768 and Ubuntu's Unity desktop requests a full gig!
Someone always pops up and cries out "but our computers are so powerful it doesn't matter" whenever you mention system requirements these days. The fact remains though - it does matter. A desktop that runs fast on a slow system will fly on a quick system. Resources should be there for your applications to use, not for your desktop environment to eat up. Trim as Enlightenment already is, the developers are currently in the process of rewriting all of it's code to utilize XCB to replace XLib - which will make it even faster.
A Flexible Environment
While KDE has a fair bit of configuration options, the developers behind Gnome 3 and Unity have decided that taking control away from the end user is a good thing. I'm sure this denial of user choice is tailored after Apple's OSX - which has about as many configuration options as a Model-T Ford. If you don't let the user customize things they can't possibly break things right?
The Enlightenment desktop doesn't assume it's users are morons and doesn't assume you are using it on a small touch screen device. It gives you the power to do with it as you will. You can leave it at the defaults or configure it to your liking.
Enlightenment can do a full restart of it's desktop environment without affecting the state of any of the currently running applications. While this may not seem entirely useful, this feature is a blessing when your desktop of choice has an "opps" and crashes. I'm sure if Unity or Gnome 3 had this feature it would have saved many users lots of grief in the last few months.
Run Everything Tool
I'm not going to go into everything the Everything tool can do here - but to list a few features it can act as a system menu, quick launcher, web search, file finder and much more.
What do you think? Are any of my points here valid or are they way off point?