This is a good question but really tailored for each individual user. My smartphone has a 4.3" screen and it still fits ok in my pocket. A larger screen would be good some some applications like google maps, videos, and some games, but i would need it to still be able to fit in my pocket as i don't want to carry a bag with me every time i go out. Of course for the ladies it's less of an issue as they keep it in their handbag. I prefer not to use a manbag everytime i leave the house.