My daughter received the unit from her mother with a broken glass. Having just replaced the same on two Ipad 2 units, I thought I would fix this one also
Aside from a lot of time spent removing the shattered glass fragments, I found the Ipad 4 to be easier to replace than the Ipad 2 glass. Primarily due to the power/volume/mute cable not being exposed near the rim of the glass adhesive. Was able to gently tap the bent corners that caused the glass to crack. The ribbon cable for the screen button can be a little challenging to reinsert into the board connector, but as with all things on these apple product servicing, patience and diligence will get the job done.
Used rubbing alcohol to remove the remaining adhesive