Alot of his moves seem easy to use, and he is pretty effective against certain opponents. But he can be punished pretty well if you know what to look out for.
I was coming from playing Raiden and I felt like I wanted a more technical combo. When I watched the IGN preview for Issac, it showed how the timing needed to be percise and positioning etc. I think he's kind of a easy character. He lacks the long range attacks which means he always has to be at some middle position from everyone else (not including the Up + circle).
Plus if he get's focused like I mean 100%, maybe it's me, but he falls apart. I've seen other characters hold up on their own but not for Issac.