I've got the base model (mark II F) with the regular barrel. Zero complaints here. Mine doesn't like winchester ammo (fails to eject frequently), otherwise it functions like a dream.
I can agree with the comments about the stock being plastic and crappy, but for the price of the gun, whatever. I've always dreamed of throwing a boyds or something on it, but I never seem to have the spare cash, something else always ends up taking precedence... My one piece of advise is to check the fit around the barrel. Sometimes the stocks contact the barrel, and even if it doesn't the stock has a lot of flex in the forearm, so you might want to remove some material to make sure the barrel stays fully floated regardless of how the gun is held. Nothing 15 minutes with some sand paper doesn't fix.