On the subject of gaming controls, it really does depend on the designers using what they've got to greatest effect. On any games platform, if a game is written for the hardware, it will probably play okay. If a game is written for totally different hardware and ported carelessly, it may run into control problems.
A lot of people have made fun of Gameloft for porting games from other phones, but the upside of that is that these games were written from the ground up for a wide variety of handsets. These aren't console ports, they're phone ports, so they work fairly well on all the N-Gage handsets. Brain Challenge has absolutely no control problems whatsoever, for example, because you navigate its puzzles just like you'd navigate a phone options menu.
Phone controls are normally simpler, but it's a mistake to think simple controls mean boring games.
Anyone remember Warioware on the GBA? That used just one or two buttons in most of its games, yet it was still one of the best-reviewed handheld games ever, because it used the controls in an imaginative way.
One of the most acclaimed N-Gage games right now is Creatures Of The Deep, which has had excellent reviews across the board. Part of its genius is that it uses just one button during all the action sequences so it works just as well on any handset.
COTD is not a simple game to play though. As well as chosing the appropriate lure, reel, depth, time of day etc, during the actual fishing you have to constantly balance the strain against the amount of line left, which can be incredibly tricky for some fish. You have to let some of them get ALMOST to breaking point if you want to have a chance of catching them, which is not an easy task.
Another point is that controls generally matter more in fast-moving action games. If you're dealing with slower-paced games the controls aren't as crucial to enjoying the game.
There's also the possibility that if accelerometers and touchscreens becoming standard phone features (at the moment they're still fairly rare), phone game controls may change completely to take account of these new input methods.