My one year old daughter bit my wife's iPhone 3GS. This cause a crack in the glass and also caused damage to the LCD underneath. What started out as a single dead pixel, multiplied like a zombie infestation into a patch of dead pixels the size of a quarter before the entire right side of the screen died and the speaker stopped working.
Repair was great! Took about 10 to 15 minutes, which considering this was my first attempt at any type of electronic repair I think is pretty good and speaks to the quality of your guides. I did have to hook it in twice as I missed one of the connections the first time around. But once I took a closer look at the pictures in the guide, I saw my mistake and was able to quickly correct it. Powered up and works and looks perfect.
Don't let a 1 year old bite your iPhone.