The problems I have with mobile phone games are
- the lack comfortable and usable controls, and
- the general experience of playing on a tiny display.
Neither are things I particularly enjoy personally. I can't imagine playing a 3D shooter or anything requiring fine control on a mobile phone like
my T610 and having a fun time. A PDA, like
my Tungsten T though, different story. It has a much bigger display which doesn't give you a headache, and a control layout more suited to arcade gameplay. Tetris on a mobile, fine. Your typical Build action game, I beg to differ. I would however like to try id's Doom RPG, which with its turn-based gameplay removes the problem of reacting and maneuvering with horrible mobile phone input devices. I personally like my phones to be used for communications purposes. Listening to music is about as far as I'd go with phone extras, but unless the phone is designed with gaming in mind, it's not going to be a pleasurable gameplay experience. Plus, game-oriented phones end up being more of a game console and less useful as a phone. I hope one day a manufacturer can make a device that is balanced and doesn't make you look like a git using it.
Jonathon