He isn't the only one who thinks so at all. If you were to compare their attributes and achievements in football, any independant person would surely say that there is little to choose between them.
Personally, I prefer him to Fryatt for his pace and finishing ability. I think that he is of a better overall quality. The negatives are his injury record and apparent inability to settle at the club.
Also, just because someone is unhappy and wants to leave doesn't mean that person has a bad attitude. Fryatt had a 'bad attitude' last season when Martin Allen played him on the wing in preseason and made it clear he wasn't in favour - what's the difference? Campbell has never demonstrated a bad attitude anywhere else he's played.