I thought it was...ok, roughly on the level of Ep III.
As others have already said, I didn't like that it was basically a re-imagining of Ep IV. I mean, another planet-destroying weapon? Really? C'mon JJ, you're better than that. Stop playing it safe, and be a bit more daring.
Absolutely hated the Finn character, though. So bland, so pointless. The actor was also terrible (as was the guy playing the pilot). Generally, the movie had way too much Hollywood about it for my taste. "Here's a strong, independent woman. Here's a token black guy who makes funny faces." Bleh, so forced and formulaic. What's next? The big reveal that C3PO is gay?
Still, when the credits rolled, I thought "That's it?". I genuinely believed we had at least one more hour to go. So I guess it was pretty entertaining. I maintain hope that the next 2 movies will be more original, though.
Maybe I'm just too old for these bland vanilla stories. I guess I would've loved it if I was still 12.
Oh, and while we're on topic: please, stop saying the prequels weren't bad (which I've read quite a few times, recently). They were terrible (at least Ep I & II). It's really not a matter of opinion. It's basically "The Muppets on Tatooine". Ep II is one big, boring love story, with crappy dialogue, and two actors with absolutely no chemistry. It's ok if you like them, I like some bad movies, too. It's also ok if you were young when you watched them, and they hold some nostalgic value for you. Doesn't change anything, though, they're absolutely mind-numbingly bad movies, Star Wars or not.