I installed iOS8 on my iPad and iPhone yesterday. I am disappointed with iOS8 on the iPad2. It is fine on the iPhone 5. On the iPad2 apps are appreciably slower opening. After that it runs ok but seem slightly sluggish than before. Looking on the net it would seem that I'm not the only one experiencing this. iOS8 may be a step too far for the iPad2. Be careful with upgrades if you have an iPad2.
I have installed 8.0.2 on my iPad2. Had a major snag in that I had to do a restore from my back up and after recover of all my apps and 8.0.2 install found I had 25 updates for the apps. Too early to state if 8.0.2 is an improvement but will report back.