I think API-wise the most important improvements were done with Kitkat and the 4.x series. Targetting that will get you pretty much all the users you need. So i

I think API-wise the most important improvements were done with Kitkat and the 4.x series. Targetting that will get you pretty much all the users you need. So it's not as bad as when 4.x was new and the majority of users were on 2.x. That said, I agree it's hard to be enthusiastic about a new Android-release these days. It's even harder to find out what new stuff (which isn't tied to US-only offered Google services) which you have in store as a user. On the bright side, that's probably a sign of a previously immature platform finally maturing.