My iPad 2 is still going strong after two years of continuous daily use. It also received every update......until iOS 8. I updated the afternoon iOS 8 was released. For two days I struggled with -
Open Safari to a web page, get up, pour a up coffee, sit back down, and a short few minutes later that the page pops up. Read a story that required going to next page? Another cup of coffee and boredom. It was like Apple gave me a time machine to go back to when I first got the internet in the 90's. Same experience - slow.
Click on an app I just used before updating......screen goes black, then it goes back to the home screen. Hit it again, stays on the black screen a little longer, then goes to home screen. A few work but most either don't or are sssllllloooowww.
Turn the iPad on after removing it from the charger at 100%, try to load a few websites, suddenly the battery shows 79%. Give up on the net and watch a movie....halfway through it register 39%. Right before the end of the movie the "Less than 10%" remaining pops up. As the credits roll the iPad shuts down. This never happened with iOS 7.
So I roll back to 7.1.2 which instantly returns it's speed and stability. I'm still working on adjusting stuff to improve battery life. Lesson learned - my 2 has had it's last update and 7.1.2 will be it.