What makes some cell phones worth ten times others?

when you use your phone day in day out for research an much more than just a phone or camera the quality of the screen resolution responsiveness of the touch screen processor speed and the overall experience of just using it come into play. i own 2 of the phones in the $100 dollar price range a Alcatel and a lg i use them as bluetooth music players so i don't have to tie up my regular phone. they work good for that but would pi** me off trying to use them every day i guess i am spoiled