I always hate new Doctors at first, in part because I've yet to see a regeneration sequence that provides a good picture of what the new guy's going to be like. The other part is that, once you've become attached to seeing one actor play a character, it's difficult to switch gears and accept an interloper.
To be fair, I gave this Doctor the same amount of time to wow me that I gave every other Doctor: one episode. Peter Davidson won me over with The Caves of Androzani, Christopher Eccleston got me with Rose, and David Tennant - with the help of an errant satsuma - helped me get past the fact that he didn't look like Eccleston.
Matt Smith earned my grudging respect with "Beans are evil. Bad, bad beans" and "I'm the Doctor; I'm worse than everybody's aunt... and that's not how I'm introducing myself." Then, somewhere between fish custard and "Yes, I kept the clothes" he became the new Doctor for me.
So, great job Matt Smith - and all the actors, writers, and other people involved in The Eleventh Hour.
. . . But I'm still dressing up as the fifth Doctor for Halloween. Sorry!