I had some trouble with the first part of the Times Square level, Azeltor, and the part where you drain the slime on Professional, but was otherwise okay. I had already played through once at that point, so I knew most of the ghosts' weaknesses and how they attacked plus where to go and all that. Probably made it a bit easier.
Strangely enough, I did the stone angel part in one try on professional. Must have taken me at least five on normal. Hell I have a hard time playing that part on easy sometimes.