Indeed it is open. 

Just so this is clear since I've gotten five or six PMs from various applicants about this.

Angels are off limits. This may change at some point but for the moment you can't play an angel.

Demons are Evil. If you play a demon then you are one of the bad guys. I have no problem with this, indeed I think it would add a good variety but there are no Demons on the DIS team.