[kahljorn]

yea. Like I said ive only played the first one really, but it's cool because he gets fun upgrades. Probably the coolest upgrade besides the one you get near the end-game is these things that go on his feet so he can slide and jump really far and also climb up walls and stuff like that. I think you also get armor upgrades... they are upgrades left behind by that dr. guy.
and there's a weapon upgrade you get towards the end of the game which makes it so you can charge your weapon (so you don't just shoot little orange balls out all the time). I think you can charge it before that too, though, but only half-way. Once you get the weapon upgrade at the end of the game though you can charge it till it turns pink and it shoots out a super attack. After you get that you can also charge all of the weapons you get from the robot bosses. So, for example, you can charge the chameleon's weapon and it will make you "Chameleon-like" and when you're in that state you can't be hit by an attack (I think if you attack it goes away, though). With the wind robots guy you can shoot out crazy tornados. The armadello guys can be charged so it turns into a shield which deflects shots. You end up needing all that stuff to get through the last few levels.
i always thought it was really fun.