Biggest mistake I made was playing through on HARD first... Shouldn't have done that, made several parts really frustrating.
I found the end fight utterly annoying too, an almost totally different gameplay style. Which I had to play through twice (sorta).
Mostly it was enjoyable. Buggy on PC tho.
Big improvement over WfC, especially now that transforming actually makes a difference.
Seems odd that I couldn't play as Shockwave, and it didn't show him replacing his arm. Was too close to the end of the game I guess.