Just checked out Owen Stephens' Genius Guide to the Dragonrider, after his ‪#‎microfeats‬ post this morning on FB. If dragonriders are something that interest you, you need to have this. If you're on the fence about dragonriders, you should seriously consider picking this up. Owen's "focus" mechanic is a brilliant way to balance out, not only the number of actions the PC/dragon can take in a round, but the power you're dealing with. It's a mechanic I wish they had incorporated into familiars, summoned creatures, animal companions, etc. Nothing slows down play like a druid with a companion who has just summoned a several metric tons of claws and teeth.

The dragonriders themselves are decent in a fight (Full BAB, monk-like saves), but only wear light armor, have limited weapons and very limited selection of spells. Still, these features compliment their companion well. The focus is on the dragonrider/dragon combo, not one or the other. Even the explanation behind why an intelligent dragon would bond with a humanoid rider makes sense, game-wise at least.