The Galleria dell' Accademia is visited by hordes of tourists every year, primarily for a chance to view Michaelangelo's statue of David. The unfortunate truth is there not much else to recommend this small and expensive museum, which often has lines that wait over an hour for entrance.
David is pretty impressive, and much larger than you might expect. It's a little funny looking at him up close in that his hands look enormous and disproportionate. Michaelangelo's statue tited Slaves is also on display at the Accademia, and it is a beautiful work that evokes a sense of movement from its quite still marble.
The other works on display are pretty unexciting, though there is a Boticelli of Madonna and Child. If there is a huge crowd outside, try coming back later and to lessen the frustration fo what may turn out to be a pretty quick visit to the Accademia.