My iPhone 4 is still on 4.3.5. I won't download it because of all the problems I've read about it. The battery drain already increased noticeably with the 4.x.x releases. Don't remember which one really triggered it. But I can't afford for my battery to drain any faster than it already is.
I downloaded ios5 to my iPad and went from a battery that seemed like it lasted forever to a battery that I'm having to charge every couple of days. Really, really sharp decline in performance.
Very disappointed that this hasn't been resolved and, once again, still seems to be a case of Apple saying, "well not EVERYBODY has the problem, so there's not really any problem to address." The ios version of "you're holding it wrong."
Frustrating.