Is an aquarium right for you?
I often meet people in their late teens and early twenties who are interested in getting a reef tank. My inclination is to talk them out of the big stuff, if not trying to talk them out of it completely. Fish tanks are like massive social life anchors--forget about long vacations, extended work travel, or moving with ease. There's always time in one's life to start this hobby. Why rush it?
If I haven't scared you off yet (and I hope that I haven't), I can say this for sure: If you're willing to put up with all the inital frustration of learning, can tolerate the loss of livestock, and get over spilling copious amounts of water on your carpet or hardwood floors, you will almost certainly enjoy this hobby. For those of us who live in big cities, it may be the only opportunity for us to have some form of living "garden".