I miss the old Reunion Arena but it can't even compete with American Airlines Center. If you plan on sitting on the upper level, 326 is as good as it's going to get. If you're a fan that enjoys the x's and o's of the game, 326 is great. You can see which defensive and offensive plays are ran with perfection. You'll be on the same side of the arena as both the Mavericks and visitors bench.
All of the seats are individual seats. There are no bleachers but you had better pray that you get seated next to a smaller person because the upper level seats don't have a ton of elbow space. I think most arenas are like that.

American Airlines Center is one venue where it wouldn't hurt to bring binoculars. They rent them to fans on the main level, that should tell you something. There are three levels of seating and this is one of the larger NBA arenas of the 29. Just a heads up.

The Jack Daniels bar in the northeast corner of the arena is super nice and the downstairs part overlooks the Mavericks practice basketball court. This place also has great visuals and the surround sound and team introductions are super loud, be advised.