It's a good MOC, but not a good representation of the AAT. Maybe call it a prototype AAT, because it doesn't resemble the AAT, except in the frontal dish.
If you want to make a real version of the AAT, and I mean really based on the actual vehicle, you should first look it up on Wookieepedia. It would really help if you knew exactly what a ship looked like before you built it. ;)
image of the actual tank: http://images3.wikia.nocookie.net/starwars/images/d/dc/AAT.jpg
There are a few things you can improve on here: First, the "arm" cannons need to be extended out further, the hull needs to be wider in general both in front and in back, and the turret could be wider as well.
Hopefully my comment was useful, yes?