MM2 was pretty easy actually. Even difficult mode wasn't so bad. The only hard part is Bubeam trap, and if you're REALLY stuck, you can get around it with an exploit (crash bomb all walls, die, refill crash bombs, face Bubeam trap without crash bomb walls).
But if you think it was hard, the other Mega Man games will have you pulling your hair out. Especially 7 and 10.