I dropped my iPhone 3GS and ended up with a strip of my touch screen not working. Everything was displayed properly but I the touch functionality of a small, but important strip was damaged.
The online instructions were great. When I first lifted out the old display assembly I was not sure how the cables were disconnected. However, just like the instructions said I just used the spudger and the cables came undone.
Read the directions through before starting. Follow along with the instructions as you are going. When you finally settle the display assembly in, ensure that the rubber gasket is pushed in around the bottom of the display and that the display fully seats into the case.