A great expansion to one of the best multiplayer games of all time.
Special Forces delivers a bunch of cool new maps. There is one map were you are on a submarine and you ether have to try and board the submarine or defend it. The biggest new character class is the British which brings a bunch of cool new guns to Battlefield 2. This game is only an expansion pack so it adds a few more levels to Battlefield 2 so it may not last long. But, most of the maps are a lot of fun, and you will want to play them again and again.
The graphics still look really good but didn't notice any changes from Battlefield 2.
The sound still sounds very realistic. You still get the feeling that you are in the middle of a battlefield. The Battlefield series always seems to capture the sound of war perfectly.
If you want more Battlefield 2 action then you should play Battlefield 2 Special Forces.