I am not saying your current games are bad - I have no experience with them
You've saved yourself some money and hours of crappy gameplay then. Assassin's Creed was almost enjoyable (if it hadn't been so buggy), other than that I haven't really enjoyed an Ubisoft title since Chaos Theory (released in 2005). I had been looking forward to Splinter Cell Conviction, however with the way they keep delaying it and changing things by the time we get it I doubt it will resemble the original franchise at all.
A note to game developers: Just because a franchise is successful doesn't mean that it will survive a substantial change in gameplay like we got with Double Agent. Furthermore, after a bomb like Double Agent it would be wise to return more towards the style that popularized your game in the first place before branching out in new directions. I'm not asking for EA Games Madden-esque repetition here and not saying that taking franchises in new creative directions is not good, but when you fail so badly take it back to base before you try again.
Also: If you notice game sales going down it probably has a correlation to your games sucking, regardless of the actual effects of piracy. Since the industry has pretty much stopped offering demos often times the only way to try a game is to download it first. If it sucks why would you bother purchasing it? "Better" DRM isn't going to help you on this front, however games that don't suck would. =)