I really wanted to hate it, because it was so overhyped, but I'll be honest, I liked it. I thought it would be like The Royal Tenenbaums, some insufferable, too-cool-for-school, irony-filled hipster comedy. But it isn't! And these days, that's saying a lot!
The DVD had alternate endings, and, interestingly enough, one of them is actually much better than the real ending. Best of all, according to the commentary, that superior ending was thought up by Abigail Breslin, the young girl who (with help from Alan Arkin, a favorite of mine from Slums of Beverly Hills) steals the movie. The whole point of the movie is that the youthful exuberance of the girl and her grandfather trumps all the self-absorbed, overserious worries of everyone around them. Yet the directors' ignore their own point, and instead of ending with Abigail's very fun and unique idea, end on a completely typical and overused note.
Anyway (spoiler alert I guess), the movie is nothing too special, but it certainly has its moments, and the best among them is the instant classic dance scene, so here it is, hope you like it!