Are you able to come down here and check things out before your PCS? That way you can get an idea of traffic, commute times, neighborhoods, etc. It's REALLY difficult to do online. We originally lived in Old San Juan but moved into housing when things didn't work out (you can read some of my earlier posts).
I just wrote an article for the sector on living on the economy for their updated Helpful Hints document - I'd be happy to send it to you if you'd like.