The touch interface works pretty well. It is responsive, pretty quick and fairly accurate. I still occasionally open the wrong thing by mistake but I have been pleasantly surprised to see it pick up small links I touch with my fingers and not get confused by surrounding material. I don’t think it is any worse than the iPod Touch.
The one thing about the version of the N97 I tried out is that it doesn’t have a full screen QWERTY keyboard. This is probably because it has a physical keyboard. It does have the other options though. As far as I can remember (I don’t have the pre-release device at the moment, I sent it back for some testing) there is an onscreen keyboard for text messaging when the physical keyboard is closed.