It is great stuff. Isn't the risk that carbon fiber is designed to take loads in certain directions, but not all directions? I've heard about carbon fiber bicycle frames snapping like twigs because the force came from an unexpected direction. The other problem, aesthetically, is that it yellows when left in the sun. (I've seen this on Porsche GT's, and when people replace hoods and spoilers on their cars with carbon fiber versions.) Also, they make carbon fiber surfboards now, although they're black, and in the sun, surf-wax cannot stay on them due to the heat.
Early carbon fiber bikes were prone to breakage, but I don't think that's an issue anymore- the technology has come a long way since the '80s. I have one with over 20,000 miles on it, and that includes some nasty shocks from potholes. The frame still rides like new. Although I don't leave it outside it has seen its fair share of sunlight, and it still looks great (when I clean it up that is).