The biggest pitfall by far is that you will like it so much you will add on, and add on and add on.........
You get very used to one bedrooms and can't handle a studio (no wash/dryer, kitchen, kids in your room.....)
Two major expenses every year are annual passes (if you go that route) and the maintenence fee (some people spread it out).
Interest rates are also pretty high (around 10%)
Overall, there are no pitfalls that I can think of...