This was, I guess still is, one of my main concerns. Pretty much my only concern other than battery life. I am a big guy, 6 foot 8, and when I had an Inspire it fit great in my pocket. The large screen size was awesome for viewing the 'net and YouTube. But it was a little heavy and cumbersome to carry around. My friends with Droids all say you get used to it in about 1-2 weeks. After that you won't want to use a smaller screen. I had the Inspire about 1 week before I returned it because of slow internet speeds. The size was a touch annoying, but the display was soooo purdy.
We've got 14-30 days to return the beast if it doesn't work out. So that's nice. I am currently working on a 4 inch screen and I think that is just the right size. But not many good phones have that size, certainly none I want to keep for the next 2 years. This Samsung Galaxy S 4G is no good. But that could be t-mobile's network and not the phone.