Yeah, I doubt there being any problems getting this phone. You may experience lines though depending on if AT&T is somehow releasing another phone the same day but so far there is no word on that.
I have mentioned this before, AT&T picks random devices to go up for pre-order. I think the devices they do pick for pre-order are just those they want to get a feel for in terms of how many people demand a device like it. I think its more of a R&D thing so that if they get a lot of pre-orders then they will want to bring more devices like that. For example, one of the random devices they chose was the HTC Status (the facebook phone) and I think they chose that for pre-order to see how many people like having a stupid facebook phone or not. Obviously, it was very few.