Yes, I'm on it occasionally. I use rollers, which can be a bit disorientating when you go round corners (I find the same using Sufferfest videos with TrainerRoads!). I'm on the Mac version, which didn't work at all for ages, but an update last month finally got it working for me.
As yet there are no training workout, though they're coming. The social side is really good, and some people have done several thousand kms round the two courses we've had so far. I also have a BKool trainer, and I have to say though it's good for structured training, it's nowhere near as much fun! It would be good if BKool would release their Private Ant+ protocols to Zwift so the program could control the trainer's resistance. There have been hints that they may do so, so I'll hang on to it for now.