My dear wife's 3g fell out her pocket getting out of the car, breaking the front panel. My daughter's 3gs slipped out of her hand shattering the front panel.
The repair on both phones went smoothly. The step by step instructions gave me confidence through the whole process. The adhesive backing is a bit tricky to get off, but once an edge is loosened it comes right off.
Order your complete kit from a reputable seller like iFixit. It may cost a bit more, but you have confidence that you are using the proper parts and have everything you need.
Be PATIENT when applying heat to loosen adhesive. The right amount of heat and it comes right off. Heat also loosens the residue adhesive so it just peels off.