I found them pretty easy to assemble and they are quite comfortable to sit on.  Everything needed to assemble is included, even Allen wrench and a cute little reversible screwdriver.  The stools look very similar to some far more expensive stools we had seen elsewhere.  The instruction say to leave the bolts loose and drop the stool a few centimeters onto hard floor to level the legs then tighten, however one of my stools still wobbles just a bit as the legs didn't end up quite even.  Nonetheless, it's hardly noticeable and I would buy again.

Pros: Look great.
Cons: Slight wobble possible