I'm a big fan of Coogan, Keener and Poehler, and a huge comedy nerd, but the movie was horrible. No consistency of tone, Coogan was as unfunny as I've ever seen him, and the kids are just unspeakably unfunny and bad at acting.
Saw that on DVD this weekend and I thought it was hilarious. Obviously it was intentionally formatted as a typical inspirational teacher movie, and the writers managed to twist the format quite effectively while keeping the outer shell. Arquette's character was really the only negative for me - otherwise a good laugh. Catherine Keener has such an interesting comedic power - she's just really funny in a complex, disturbing way.
Did not like it. It almost seemed like there was a funnier movie in there that got edited out. You can view this as working satirically within the format of a typical movie or just being hemmed in by that format. It also tried to lampoon cliches and still trade in them, on a level only a little funnier than the "Epic Movie" style jokes.
And the actual musical scenes were just not good enough to justify themselves.