Are you looking at Internet only or TV and phone, too? What services do you qualify for? The answer to your question is "it depends". With Uverse, the connection to your premises is almost always not fiber. Less than 1% of Uverse neighborhoods actually have FTTP. It is almost always copper from the CO, IRAD, or VRAD to your house.
So, assuming it is a copper connection to your location, the quality of the service all depends upon how far you are from the serving terminal and the quality of the copper you are connecting on. If you are more than 3000 feet you may not qualify for much in the way of speed. Also the further out you are, the greater the potential for line interference and signal degradation which can cause intermittent issues. If you happen to be close enough within 2200 feet or so of a VRAD and the copper is in decent shape, you should expect to get pretty good service.
Uverse has been rock solid for me on the 24Meg plan but I happen to be only 1323 feet from the VRAD. I also just upgraded to the new 45Meg Power tier this week and I have been averaging 46-47Meg down, even with multiple TVs watching live video streams.
Unfortunately, every customer's experience can be different depending on the circumstances. Your best bet is to post in the AT&T Direct forum
and ask to get your line pre-qualified. You can actually get real info about your line capabilities from the Techs who participate in that forum. It may take them a day or two to respond, depending on how busy they are, but they will eventually get the info you need. If you post in there, follow the forum rules and do not reply to your post, until a tech responds to you or you will get lost in their queue.--
Scott, CCIE #14618 Routing & Switching