According to most people on the internet, the game is horribly unoptimised on PC. It only uses two cores and a maximum of two threads even though they said in a interview before hand that it will make use of four to six cores. In the same interview, they promised 60FPS on a 670 with most settings turned up to the max. In reality, you'll get somewhat close to that, but it'll jump around a lot (anywhere from 40 to 60; doesn't really matter what graphics settings you use. High or low runs basically the same). Most of the people who have been able to run it at a constant 60FPS were the guys with Titans or 780's. I'll acknowledge that AC4 looks good, but it definitely shouldn't need a Titan to run it at full settings at 60FPS. The port is fine, but the optimising is definitely lacking.
I would've hoped that after AC3, which still has issues on a lot of systems, that they would've learnt their lesson. Now even though the PC version is the best looking version, and a decent port, it needs some optimisation patches. Ubisoft, seriously stop giving the job to Ubisoft Kiev, get the guys that did the Splinter Cell Blacklist, Rayman Legends or Far Cry 3 to do it. How can they be so inconsistent? It makes no sense
I'm really looking forward to playing it but when they say that they develop primary on PC, it has to be a lie. At the very least the bugs are kind of funny. The Flying Dutchman one is incredibly amusing.
Also, I heard that there was a day 1 patch. Does anyone have a link for that?