If you qualify, this is a great deal. The unfortunate part of patent prosecution is attorneys fees, which are largely the result of the complexity of the prosecution process, and the AIA did little to help that. However, this is a nice start. Also, per my previous post on small claims courts for patent litigation, small inventors may have a significantly greater chance to participate in the patent game.
More details on the micro-entities are expalined at http://www.uspto.gov/aia_implementation/.