2 - 5 Minuten
Thing 4 has been the owner of a hand-me-down iPhone 4 for a couple of years while he waits for all of us to upgrade to the model being released in Fall 2014.
He is generally very careful with his electronics, but he ended up dropping his phone recently on asphalt and severely cracked the front screen. Since we are expecting that we'll be getting new phones for everyone this fall I told him to just suffer through it. Until one of his friends dropped it a second time... This time the cracks were shedding glass splinters so something had to be done.
Enter iFixit. I had used iFixit guides and their parts to replace a couple of 3GS batteries and an iPad v1 display with great success previously. The guides were clear in both photos and written instructions and the parts were affordable with quick free shipping.
The install itself was actually very quick. We used an empty egg carton to hold the screws/parts in numbered compartments. The included tools were very helpful and the drivers were magnetized which was a great help.
After about 90 minutes (extra time likely due to Thing 4 and I being slow and from having to repeat some steps to remove the display and feed the ribbon correctly) the device powered up and everything was back in business.
Only real challenge was making sure that the display/digitizer ribbon was *completely* fed through the slot in the case. If you don't feed it in all the way it will *not* reach to reconnect.
The egg carton (Thing 4's idea) is a great way to hold the parts you remove from your phone, make sure that they don't wander onto the floor, and let you number things exactly for easy reassembly.