Just saw it last night with Hangman. I thought it was funny and will probably be funnier each time that I watch it. However, the one thing that it didn't have that Napoleon Dynamite DID have, is a plethora of developed characters. For the most part, it was just Jack Black (Nacho) and his sidekick, Esqueleto. There were a lot of funny and funny-looking characters, but we didn't get to see them for long.
Don't get me wrong, it's a fun movie. If you're a Jack Black fan and/or a Jared Hess fan, you'll enjoy it.