You can look at my previous posts above where I state that iOS 9 on my iPad 2 is OK, but if I had it to do over again I would NEVER have upgraded from iOS 7. The slowdown in performance is significant and very irritating. In the last two months or so, I've pretty much stopped using my iPad 2 as a result.
If you want the latest functionality you should get an iPad Air or Air 2. And if you look at the big picture they aren't that expensive if you get a low end or refurbed unit. When the successor to the iPad Air 2 is announced and the prices for the Air and Air 2 drop even more that's what I'm going to do.