well, you HAVE to stay in the mileage requirements of the dealer. Often they say you cant put "X" number of miles on a leased car before you return it...if you do, you gotta ay a penalty.
Also, they require the car to be in good condition when you return it., no big dents or srapes, and the interior has to be nice. My final dislike about leasing is that the car isn't really "your". youre borrowing it, and you HAVE to hold onto it until the lease is done.... you cant go selling it wheneever you like, driving it as far as you'd like, etc.
It makes sense for people who dont have the money at start, but can keep on putting a portion of their paycheck to it each month.
Personally, I'd rather just save my money until I can afford a car straight-up.