I haven't done much reading about the n-gage, but from what I've heard I wouldn't waste your money. The n-gage certainly isn't a very great phone since you have to hold the long/skinny face to the side of your head like holding a taco from the sides.
If you really just want to play games, the Game Boy Advance is probably as good as it gets until the next round of portables (Playstation Portable) are released. You have no idea how enjoyable it is to play Zelda: A Link to the Past on GBA. On top of that, there is Sonic Advance and Mario World 1/2 along with Mario Bros. 2/3
