I usually wait until the new version is released before trying it. Also, I never update. Nor install patches. I usually end up with an unusable mess. Instead each version goes in its own directory. And each uses its own workspace. So currently I am running both 3.6 and 3.7 with only a few projects movie to the 3.7 workspace. So far I haven't come across anything spectacular but then I mostly use Eclipse as a glorified text editor.
I downloaded it the week it came out. Here's my thoughts on what I liked/didn't. For personal use, I upgrade as soon as it comes out and I have time. Last year, Iw as studying for a cert and delayed a lot. This year, I had just gotten a new computer a bit before release and held off on installing Eclipse until 3.7 was out so I downloaded on release day. On my work machine, I wait longer. Until I need some new feature or the new version of Java or there is a reason to.