I use folders on both my ipad and ipod touch. I have more on my ipod as I have more apps. On my ipad I have folders for Navigation, productivity, news, social, shopping, games, reference, magazines and comics. I don't like having too many screens just full of rows and rows of apps, it feels disorganised to me
I organise my screens according to most to least used apps, with most used in the first screens and least used on the back screens.