To be honest, Neal didn't know what to feel. He hurt James, he knew it, but what he said was also the truth. Well, the truth hurts, both ways. Of course the matter was compounded when he blamed his father for his own failure. His own failure to make it as a legitimate artist...well, after all that has happened, as legit as Neal can make him that is. It is unfair to say that James was to blame for his identities and aliases and hence his failure.
To be an artist you have to know who you are. He knew who he is. He is Neal Caffrey - world greatest art forger. He could very well make a new identity and make it into the art world. He'd be great. The true reason behind his lack of originals was because there was no one who would praise and appreciate his works. Except Mozzie and even then he complains that it would make them nothing and Neal should stick with forgeries. At least those he can fence. At least those are appreciated. At least those are recognized.
But maybe things have changed now. Daddy appreciates. Daddy is proud. Maybe, just maybe, Neal can make it...as long as dad approves. And to be honest, Neal didn't know what to feel about that.