My niece has been wanting a iPhone 4 for forever!! Well, I handed down an iPhone that i bought May of last year to my nephew after the iPhone 4S came out last October. My nephew dropped the iPhone 3 weeks ago, so he stopped using the phone and bought a used one off of Ebay. My niece asked her mom if she could use the iPhone 4 even though the screen was smashed. Her mom said yes. I couldn't stand to see a broken iPhone so I bought the tools for www.ifixit.com and the rest is history!! Perfectly working iPhone!!!
The repair took 1.5 hours and there were absolutely no problems. I took breaks and deep breaths frequently.
The only thing I wish I had known before starting the repair would be how difficult it was to remove the battery or anything else that was glued down.