I myself am not playing one, but I am GMing a game where one of the players is one. They are only level 3, but so far its actually a very interesting class and he seems to be enjoying it. It's a strange class in that I certainly would normally never allow a gun class, but this is a high fantasy pirate campaign so it works well.
Its a small 3 man party with no healers or tanks and so far the gunslinger is out performing the other 2 in combat. The ability to ignore armor comes in VERY handy. So far the level 1 deeds all seem pretty useless, he hasn't needed to use one yet. Hoping now he get a level 3 one he will get to show it off a bit more.