Of course he's different, as almost every individual player is. The fact remains though that if Fellaini plays, Cleverley or Carrick won't. This means that you have to compare his "up side" to theirs, as you will be losing their qualities to accommodate his qualities... Do you follow? Who would you have us compare him to if not someone whose qualities we will "lose" to accommodate him?
Again I am not disagreeing that Carroll was ludicrously expensive. But the point remains that just because United (or Liverpool, or any club) decide to spend a large fee on a player doesn't instantly mean he will be a success, or is worth the fee, or that any slightly cynical person must be chastised or lambasted until proven conclusively right. Everyone is entitled to an opinion of any player; mine is that Fellaini will be a decent-good squad signing but is firstly never going to be "a £27.5m" (or £23.5m) player and secondly will not be anything special. This doesn't mean I've written him off and doesn't mean I'm waiting for him to fail. Likewise it doesn't mean I don't want him to succeed; if he turns out to be the next Yaya Toure it could make us a dominant force for years to come and I'll be delighted.
I hate the fact that people still believe that Carrick wasn't appreciated because he isn't glamorous. Carrick wasn't appreciated 5 years ago because he wasn't playing well enough to be appreciated. It is only the last 2-3 seasons he's really stepped up. Bizarrely enough a few months after he did make that step up, he started to get appreciated by the fans.
This moronic notion that fans only rate small Brazilian players with "inho" or "aldo" in there name is just that, moronic. If Fellaini comes in and plays very well consistently I will happily concede that I misjudged him and all our fans will give him every credit that his performances deserve (just as Carrick now receives and every other top player before him). I am somewhat skeptical however that if he shows himself as merely a decent overpriced squad option the other side of the opinion poll will concede as such. I imagine that learned fans such as yourself will champion the "unglamorous" job that he is doing and shoot down everyone else as merely not understanding what he does for the team.
/edit: Oh and I still think Kagawa has absolutely everything to prove in a red shirt and should only get in the side on merit (which he hasn't yet done).