Been playing around with my Nokia 5230 for a while, and found that there are times when I need a stylus, other times I don't.
When doing handwriting, you do need a stylus.
The virtual keyboard's buttons are large enough, and it's sensitive enough so that you don't hit the wrong buttons when typing in a SMS with your fingers. (In contrast, the LG KS360 was very sensitive, and you tend to hit the wrong button more than once).
It also depends on the size of the screen, if it's a small screen, then you'll be better off by using a stylus. If the screen is large enough to allow you to use a virtual keyboard, then you don't need a stylus.
Just don't lose the stylus though...

Great for that itch inside the ear
