I've shot them a whole bunch, and I like the heck out of mine. It's a little odd to get used to working with a bull pup, but I think the advantages (maneuverability, especially in and around vehicles, ease of carry, etc.) outweigh the disadvantages. Gabe Suarez has done a lot of work with bull pups, and I'd have to say he's the go-to guy at this point. The trigger isn't bad (better than the Steyr AUG and the FS-2000, a gun I almost bought, but it will be MUCH MUCH better with the Gieselle or Timney replacement!
I want to do a carbine class with mine later this year. Mine is topped with a Lucid red dot sightm BTW...inexpensive and really nice!
Michael B