From the clips I've seen it looks to be an excellent film: quirky, heartwarming and well animated to boot. I know many people are getting tired of the CGI films that have been appearing en masse these last few years but I think this shows that perhaps their is hope for them yet. The "podcast" Pixar has been releasing for it is also pretty neat; documenting what was done to make it as well as all the food they had to learn about along the way.
At any rate I can't wait to see it when it comes out this June (the wikipedia article has the premiere dates for the UK and Australia as well as the US if you are from those parts) and even I can't help but find Remy (the rat) cute.
I suppose they consider it an ironic character for a protagonist considering how unlikeable they are in real life. Thus in this case, a rat attempting the impossible dream, it makes it that more unique and interesting to watch as well as gives the "fight of the underdog" that more of a potence throughout the film. Not to mention that the other protagonist, Linguini, a janitor that can't cook that ends up having to be a great chef in days, gives a sort of foil to the rat as well as a human counterpart to root for.