It's the size of a paperback, so I wouldn't call it a tablet. It won't do everything you expect an iPad to do, because it's not as powerful as an iPad. But will it play Android apps? Many of them, yes. I've played Angry Birds and Bejeweled on it. Netflix movies work great, I've used Documents to Go without too much of a problem. I've used Stumble Upon, Goodreads, and Adobe Reader on it. I've also used it to view and download comics.
If you're looking for something with actual computing power, this ain't it. But then, neither is the iPad. If you want to play powerful games, get a game player or buy a laptop.
I'd say the Kindle Fire is slightly better than the Nook, but in the end neither the Nook nor the Fire will be as powerful as an iPad; it just depends on what you want to do with it.
Best Buy is selling the Kindle Fire, BTW. If you have one near you, see if you can play with it while you're in-store. It may help you make up your mind.