My wife has an iPad 4 and hers is working great with 8.1.1. I don't believe 8.2 is available yet except in beta version or whatever. It's not publicly released.
Running quite well, stutters a little, certainly not as smooth as the last OS, but not slow and no major problems. Strange on startup, goes completely black after the apple logo, for about 10 seconds. My iPad Air doesn't do that.
I'm on 8.1.1