My 10-year-old son was using the iPad 2 in bed. He leaned into it with his elbow, breaking the front glass into hundreds of pieces. On the plus side, he showed it to me right away rather than hiding it in his sister's room.
Because the digitizer was seriously fractured, it took a couple of hours to painstakingly remove the glass. The iOpener helped a lot, but progress was slow because of the number of pieces that needed to be removed.
The repair guide notes a couple of places where you need to be extremely careful not to damage internal connections (the wifi antenna and the digitizer cable). Despite my extreme care, I must have damaged the cable connecting the power button at the top of the iPad, because it stopped working. (That said, I can't see any visible damage to the cable, and the mute and volume controls continue to work.) Replacing the power cable sounds at least as daunting as replacing the digitizer, so I've decided to live with the broken power button (although performing a hard reset is going to be a problem).
All in all, I'm happy with the repair, but the guide should probably mention the power cable area as another trouble spot. Looking at the comments after the fact, I see that others have run into the same issue.
It's almost impossible to be too careful when removing the digitizer glass. Watch out in the area around the power switch cable (and the wifi antenna and the digitizer cable)!