Honestly - at 16... I'd run away personally. They aren't cheap to maintain or run. Kinda eat up gas, parts aren't cheap, insurance is (extremely) high compared to other cars, and they tend to be a money hole for modifications down the road.
That being said, they are good cars. If you have mechanical abilities, you'll be able to do most of the maintenance yourself. If you care for the car, it'll do you well.
I personally would have killed myself if I had either a WRX or STi at 16 =P. I wouldn't have been in a situation to buy one, however.
Again - dunno about your personal situation, but I'd hold off for a few years.