I used to make the drive from Atlanta to Birmingham fairly regularly a few years back, at least monthly. One thing I noticed was that downtown Birmingham really did not have a lot of restaurants, and that most were located outside of the core. One of my favorites was Two Pesos (actually in Pelham, which is a close-in suburb of Birmingham) which had some really great Mexican food. Easy to find and off a major thoroughfare. Highlands Bar and Grill was also a good recommendation above.