some people like sc2's tighter controls, faster better 8-way run and step-dodges, and deeper play control.
some people prefer sc1's slightly more forgiving controls, and a less 8-way-run heavy game in general.

Not to mention stances. Those definitely go either way ... and a lot of characters have them. Nightmare in particular has a craplot of stances (like 3 or 4, it's been a while) and can cycle between them VERY quickly, making for deeper play, but also a lot less intuitive control (since the same button combo can do drastically different things in a different stance). I could definitely see disliking them, compared to the simpler system in sc1.

I like SC2 better, but only on the xbox and cube. The ps2 controllers just totally blow for fighting games. Mushy d-pads suck.