My iPhone has been a champ. I drop it all the time and no broken bits. It wasn't until I accidentally ran into the corner of a prop for a magic show that my screen finally bit the bullet. I was going to get a new phone until I found out I could legally unlock it for way less so I decided to repair the screen.
It wasn't too bad at all! I do work on cars, Lego's, and electronics so I am okay at not loosing important stuff. The instructions were great! I watched the intro video then downloaded the pdf of the instructions, followed it to the end, and reinstalled everything by going through it backwards. It started up just like normal.
In step 29 the last bullet point gives you a tip for covering your screen with tape to catch the broken pieces of glass. I know I should have read all the steps before doing anything but I read that after I started prying off the old screen. Thankfully I found and tossed all the pieces that dropped.
Also you'll notice, if your screen is cracked, there may be shards of glass still left over on the sticky tape that held your screen in. When I installed the new screen these shards weren't letting it sit flush with the housing. I decided to remove a small bit of the old tape, the spot with the shards. After that it sat flush and the rest of the install went smoothly