A friend of mine has young children that were playing on their friends iPad and, after some elevated excitement, managed to drop the iPad. The bottom corner hit the ground and the digitizer shattered.
The repair was initially difficult with the standard tools recommended. The plastic tools bend too easily with the shattered glass. After reading some tips from other users, I decided to give an exacto knife (slightly blunted) a go instead and thankfully it made a world of difference.
The iOpener worked well for me and the childrens friends are happy with the high quality product that iFixit provided.
If the glass is severely shattered, use an exacto knife to pry out the glass, the blade helps cut through stubborn adhesive too. The glass pieces shoot off everywhere so I highly recommend taping up the glass first and using eye protection. Make sure there is no glass residue or chips on the LCD or surrounding the LCD as it will scratch and possibly burst the LCD if it gets trapped under the new digitizer.
iPad 3 Front Glass/Digitizer Touch Panel Full Assembly
Phillips #0 Screwdriver
Phillips #00 Screwdriver
iFixit Opening Picks (Set of 6)
iFixit Opening Tool