I love the look of the game, and will be definately be getting it when it comes out. I love how the women (some) it are not overly sexualised, wearing suitable armour and not skimpy nothingness...
The classes look unique and interesting, but the game at the moment looks really complicated. At the moment the levels look way too visually complicated, and there seems to be way to many different classes, having to watch out/remember how to play and the dangers of all the classes. The levels do look amazing, but at the moment way to visually dynamic.
It will never replace TF2 in my mind, it just looks way too different. Also, unless Blizzard makes the game F2P, it will never truly compete with TF2. Especially without the hats. Signing up to the beta as we speak.