I have accidentally dropped mine from use height (about 5 feet) onto bitumen...it landed on one end and bounced before coming to rest face down... Only damage was a tiny scratch on one corner of the shell...screen was completely fine. Have also fallen asleep numerous times while reading ebooks & dropped it onto the floor from 2 feet or so...still no damage.
If you are really worried, its worth getting an otterbox impact case. It protects it from drops, and also makes it easier to hold. Now, whenever I hold mine without the case I feel like its about to slip through my fingers.