I didn't really hate it, but I didn't care for Blade 2 as nearly as much as the first. My problem stems from the direction in tone of the movie, and in the lost pontential.
I really feel that Blade 2 took on too much of a horror aspect, compared to the first film. I think it was a little too flashy where the first was a little more gritty, and I didn't care for the vampire creatures at all. And then there's the waste of Whistler... his return was just too simple and there was no development with it. I think they missed a real opportunity for some good conflict for Blade and his mentor Whistler...