I upgraded from the 16gb 3G, and it was worth it. This is faster on both 3g and wi-fi and to launch apps and generally do the biz. The camera is great with a function to touch the screen to set the focus where you want, can edit the videos in the phone. Everything you could ever need, high quality e mail, real browser and apps for just about everything, GPS, route planning and it even makes phone calls!!!
Voice control for calls and the ipod works well, and frankly is freakily accurate.
If you have a mobile me account, there is a feature to use the GPS via your mac (or PC) to find the phone if lost or stolen, and even wipe it remotely.
Just THE phone to own!!!!