I didn't like Jack Black at all initially...but I changed my mind completely after seeing him in some great roles. There is something genuinely likeable about the guy, and "School of Rock" is simply a wonderful film. Some of the others he did are pretty good too. He has a knack for portraying a certain kind of very ambitious (yet sloppy and essentially lazy) young rock n' roll dude totally in love with the music, but with some obvious physical drawbacks (his excess weight, his short stature, his not terribly handsome looks, and his general lack of any conventional "hunk" appeal). I've known rock n' roll guys like that, and his depiction of the type is hilarious and bang on. He makes you like him despite his general tackiness, because you understand the hunger that drives him.