No fuel stops, it's all about the tyres: Button has that hands down, he looks after them and Hamilton doesn't. This is another year when Button could, if the car is ok and he drives like he did at the end of last season, be a champion. The regulations are prime for his driving style - whether the car suites his style is another question.
Overall I think Hamilton is a better driver, Lewis has more experience at being fast and delivering results than Button, even though Button has been around longer he's spent most of it driving like a twat at the back of the field being noteworthy for not being in any way noteworthy - or if for anything, being a man not of his word (or signature).
Hamilton is more experienced with the pressure at the top, Button is going to want to come out and win on his first outing and show the world he's the best, and honestly, he really isn't. If there's a "best" that's still racing in F1 today then it's either Hamilton or Schumacher. I'll be rooting for Hamilton, but I respect either (these days, it's taken me a long time to forgive Schumacher leaving Jordan but i'm over it now :P ).