Its kinda hard to explain unless you have really used both side by side tbh, I have both and I can navigate and read web pages *much* faster on the iphone, it is just so much more "fluid" tbh. I find I had to use the stylus with the n900 wich for me made it more cumbersome. I suppose if i had to put in words i would say the input mechanisms on the 3gs are more refined and fluid to use like one quick swipe and youve zoomed in, i found with the n900 i was "swirling" for what seemed like ages, and moving the page around was jerky and not always in sync with the input.. But tbh use both side by side and you ll get my drift. But the n900 physical keyboard is one think I do miss on the 3gs. The n900 is top notch hardware let down by its os.