I'm not a big fan of them.
They're ok, and they look interesting (Bar the no faces), but they defintely attract idiots.
I was on a medieval building server yesterday, and all was going fine, slow traffic but people joined in numbers at times. However, whenever anyone joined on their own, or when there were only a few people, rather than actually building, the first thing they did was change into a Dragon.
I'll admit that myself, the host and a few others were playing as them when we took a break from building, but they're quite distracting.
I would like to see them used in a Medieval game. Roaming Dragons would be cool to kill.
I added mountpoints and overall imrpoved the dragons and am using them for the Dragon Knight class in my Medieval Siege.
That sounds really awesome. I thought they looked like vehicles at first, but was disappointed to see they couldn't be ridden.