I wouldn't try to imitate the style, just run with your own. This peice looks great, and it does have elements of both manga and western. The eyes are toned down from the usual manga size, and the character looks a little more in repose and whimsical instead of constantly animated (which is something I'm not terribly fond of in alot of manga). The best response I've found to friends like this, unless he was giving a thorough critique, is to just say "that's nice" and move on. Usually those who want to be the harshest critics are the ones who can't do what they are so critical about.