Most important aspect IMO: how to work on a team. No one cares what you know if you are a jerk to work with. Nothing kills a team more than one bad member with a poor attitude. After that it comes down to what has been mentioned in this thread.
But it is very hard to hire someone with personality issues even if they are a genius. 9 times out of 10 that comes back to bite you. They don't have to be super cuddly teddy bears because no engineer is. But if they exhibit signs of being hard to work with, cannot handle criticisms of their code within the interview, etc. that person would receive an immediate no from me.
Very few jobs allow you to work alone all the time so a team mindset is crucial to getting most projects done.
