It's fairly good size. There is a lounge area with the piano, a full bar, and the club area with a dance floor and more seating. Click this link to the panoramic map on the website. When it come sup, click on Aura Lounge for a photo tour: http://couples.com/12sw/02swPanos.htm
They play club music, though when we were there in April, there were some nights when it was empty. Check out the daily schedule because it seems to be more active on the nights when Ultimate Chocolate plays the piano. No worries though - there is always a good social scene at the resort, you just have to find it.