The only issue I am having with IOS8 on Ipad 3 is I am not getting some push notifications but I think that is because some of the app developers haven't updated.
The one major app I use that was broken on OS8 was Splashtop, which was updated with iOS 8 support the other day and now works fine. But there are a number of other less important apps that remain broken because I guess the deevlopers have already stopped supporting them anymore. They sure give up pretty fast on some and they never let the users know that they went out of business or whatever (guess that would be pretty impractical for them to do).