I had my iPhone for 3 years and it finally gave out with a short drop when taking it out of my pocket.
The repair kit was great and the instructions were 100% intuitive. It only took about 20 min to complete, and most of that was in dealing with the itty bitty screws that apple uses.
Disassemble and reassemble the device in the cardboard box the replacement screen is shipped in to lessen the likelihood of losing the tiny screws. Also, shot glasses make a very handy way of keeping track of all the separate screws.