“With Ubisoft's fantastically awful new DRM you must be online and logged in to their servers to play the games you buy. Not only was this DRM broken the very first day it was released, but now their authentication servers have failed so absolutely that no-one who legally bought their games can play them. 'At around 8am GMT, people began to complain in the Assassin's Creed 2 forum that they couldn't access the Ubisoft servers and were unable to play their games.' One can only hope that this utter failure will help to stem the tide of bad DRM.”
So, if you plan to protect your software, DRM is a bad choice.
Please help Apple, to do a better product: sign the petition to avoid iPad DRM.