I've been intrigued by the Antec Three Hundred as a budget-oriented enthusiast case, but I've got way too much on my plate as things go, so don't expect a review anytime soon. I'm sure if you ask Bill nicely, he'll do what he can to get one of these for evaluation.
The only gripe I've seen with this case so far among the reviews I've read is that just like the Antec Nine Hundred, the Three Hundred has a fairly complicated process for installing the hard drives. So if your disk-swapping habits would make a disc jockey cringe, you might be better off with a case that has a better rail system for drive mounting.