Ubisoft tried to guard against the first Assassin's Creed being leaked by deliberately introducing a performance-degrading bug into the code, to be removed only when the game was sent to be mass-produced. Unfortunately, they didn't actually tell anyone, so when the bugged version was inevitably leaked, it considerably hurt their sales because the pirates spread through word of mouth to potential legitimate buyers that the game had terrible performance even on high-end computers.
Additionally, in Assassin's Creed 2, the DRM was very poorly implemented. People who pirated the game (when it was hacked a month-and-a-half after release) reported that it had an excellent porting job and ran as well as one would expect it to on any given level of hardware. People who bought it often reported that the game's performance was dodgy at best, with inexplicable drops at random times in frames per second.
PCGAMER US starts off their review of AC2 as follows: It's brilliant. Don't buy it. This is followed by a few paragraphs explaining exactly why they don't like the DRM on it. They also say they considered including this on their final review score, but decided to only judge the game on the actual gameplay contents and not factor in the DRM.
Ubisoft's uPlay caused a lot of controversy. A lot. It requires you to remain online during play, and if even a slightest connectivity hitch occurs, you're booted from your game and lose any unsaved progress. Assassin's Creed 2 and Splinter Cell Conviction have since had the always-online requirement removed; the games must now "only" access the Internet each time they start up. And how it fares towards the legit customers? The servers used for this scheme went down not even a week after release, making the games unplayable at all for these poor souls. Ubisoft might better prepare a barbecue if they still insist on carrying this scheme from every single of their PC releases from now on.
All the fans of IL-2 Sturmovik series also got screwed over after purchasing a legit copy of the final 1946 collection of the game — which is heavily protected by SECUROM. Trying to uninstall and reinstall the game for whatever logical reason (including the need to change damaged hardware) will cause the antipirate malware SECUROM to block the game from launching. Fortunately, there are already several easy methods on how to bypass the original install (by making your own copy) and then uninstall it along with SECUROM. Fun fact : The reason your hardware could mysteriously become damaged in the first place (if your a responsible PC user) is because SECUROM's influence will gradually mess it up, which then comes full circle when you have to pay for new hardware and SECUROM will ban youfrom installing the game again on said new hardware.
Might and Magic fans have had a bit of a fun time, too, with Might and Magic Heroes VI. Ubisoft's copy protection came in the form of the Dynasty system, which rewards players with leveling items and buffs as they progress through the game. The kicker: Dynasty progress is stored in the online "Conflux". There's an offline mode, but games saved to the Conflux obviously can't be loaded offline. Players with a steady internet connection naturally figured they might as well take advantage of the Dynasty bonuses... and were treated to a series of Conflux outages during prime play-times (including a few weekends and the week after Christmas) for a while after the game's release.
The 2008 Prince of Persia game on the PC pings an unknown server every 75 seconds. While most fans didn't (and still don't) know why it did this, the most common guess is that UbiSoft was tracking the CD key and looking for duplicates.