Broken screen, broken heart. iFixit to the rescue!
1 - 2 Stunden
Dropped my iPhone 4S on the concrete sidewalk and shattered the glass. Thoughts of the commercial with the guy swiping his bloody fingers across the screen played in my head.
Repair went well. Make sure you have about 2 hours of free time, oh, yeah, and a lot of patience!
One tip that will be extremely helpful: Take 4 8 1/2 x 11 sheets of white paper and them together forming one large sheet. Any step with screws or components add them to the white sheet (in order, of course), circle them, and then put the step number in the circle. This will allow you to see which screws and components to with each step on the reassembly.