Joe's American has been around for as long as I've known Boston (20+ years). It's got a great location on the corner of Dartmouth and Newbury Street - just about the time you are starting to get hungry on a walk that started in the Boston Common.
Joe's is a traditional steak house in the "pre-Morton's" style - New Englandy, somewhat understated, and dark wood everywhere. Service is good and quick, the place is clean, but the food is ordinary.
A first glance at the menu gives this away. You'll see a bunch of New England standards, a little variety, but nothing that requires an ounce of creativity to prepare. The kitchen stamps out the food - it's fine, but dull. Drinks flow quickly - it is a "bar & grill" after all.
Joe's is a good place to stop and fuel up if you are a Boston regular and you aren't looking for anything special. However, if you want something special, save it for one of the 100 places within a four block radius.