Uhm, yeah. I have worked on stuff "graphic" related and no, I don't think it's write to harass him, but I do think it's fair to comment on his work when:
1. He's "the" character designer, not "a" character designer.
2. He has a blog about himself, that allows for commenting. It's not like I found his personal contact info and i'm calling for blood here.
3. And most important, there's a FAR difference between being told to go in a certain direction and then doing a mediocre job at it.
Anyways, of course people shouldn't go on his site and trash talk the man. But I do think it's funny that people here have NO problem completely passing judgement on other people's work... to their backs.