So a kid in my school is selling off his old nintendo ds (original model, like, pre-ndsl) for $25. I've looked at it and the condition is perfectly fine. It runs everything i've tested it with and im thinking of buying it. Im just wondering if this is worth my money, and what the differences with the old ds and the dsl are. specifically, im wondering: screen brightness difference battery difference button quality difference weight difference size difference thanks in advance.