Gaming in a cellphone really sucks. Besides the novelty of seing games run in your cellphone, it's nothing else. They're really unplayable.
I got a T68i which can't have games downloaded to, but the simple games it comes with are hard to play, even with its little joystick interface (no diagonals. wtf?).
I still love my little phone, it's very handy. If i want to game, I take my NeoGeo Pocket Color on the road, fuck the cellphone ;P