Super Mario Galaxy is going to sell a ton and CoD 4 is going too, so I wouldn´t worry too much about them. For me, Assasin's Creed is the new thing, something different and very attractive to me. I personally love it but I understand and share some of the main criticism, however I feel it does more for videogames than Super Mario Galaxy and CoD 4.
You could say that Super Mario Galaxy is unique as well, but is too unique, is not going to create school. It´s a perfect platformer full of clever designs and charm, but is not going to influence anyone to do things based on it because you can´t export the polish and the talent. And CoD 4 is another shooter with an ok campaign and a MMO as multiplayer, apart of superb technical talent, polish... which is neat but not revolutionary.
Assasin´s Creed is a first step of something I have been waiting for a lot of time in videogames, so I want it suceeds and I think it deserves it for the bravery of the team (not its producer, I don´t share the fascination for Ms Raymond).
I feel bad for Ratchet, I hope sales goes up.