Except a lot of times, there are more than a few people who never have any complaints.
My rig now is above requirements for a lot of new games, but I used to have a machine that was lower than minimum on a lot of games. I was regularly able to play games out of my machine's "league" with no problems at all. My screenshot library on Steam starts from when I had a P4 and a 5670 and was reguarly running AAA games that I had no business playing if requirements were to be believed (I only had a max res of 1330X768 with the old monitor). The new Tomb Raider ran very well on that set up. Sleeping Dogs also ran well on that. I upgraded that PC (which was a mistake) to a quad 6600 but still kept the same GPU and finally hit the wall when I got a monitor that went to 1080. Now I have a entirely new system.
The fact is, requirements are rarely accurate. You will have people on virtually every new release that exceed requirements and have problems and people below requirements that have none. It all depends on optimization. The better a game is optimized, the more likely it will work for those with lesser machines.
Considering Ubi's track record with optimizing AC games, I would bet that this one will not work as well with lesser machines than other games do, but it'd also be no surprise if it does work well enough for people to play and enjoy it. Case in point, on my old P4/5670 I was able to play the Ezio series all the way through until 3 finally said no which to this day is IMO the worst PC game in the last 5 years based simply on technical reasons and nothing to do with the quality (its crap but thats besides the point) of the gameplay.
As far as I'm concerned - on the technical + performance side of things, AC3 PC is a much better port than what the hell we got w/ Deadly Premonition PC.
At least AC3 PC would run decently on my PC - i.e. around 30 FPS at some kind of settings. With AC3 PC, I didn't have to worry about other kind of technical stability nonsense.
All stuff I had to deal with on Deadly Premonition PC include slow-downs, stutters, sudden crashes to desktops, having to run game for about 1-3 hours before it would crash, injecting DPFix to unlock it from 720p, run a 3rd party LAA (Large Address Awareness) program just to keep the game from crashing in shorter time-frames, run the game in Windows 98 Compatibility Mode (game crashes more often, if you don't do this), and save often just in case any nonsense could occur that'd CTD me (causing me to lose any progress made since my last save). The framerate would start at 60 FPS and then slowly but surely drop to an eventual crawl (think like single-digit to 10 FPS, normally) until it decides to CTD. Deadly Premonition PC has NO graphical settings - meaning, once it decides to runs like garbage (likely from some kind of memory-leak bug, I'd guess), you're screwed.
Hopefully, before it gets bad, performance-wise - you've made your save; quit out the game; and then boot the game-up from scratch again.