Played the pc version all day today, love it so much more then the 360 version without a doubt.
The little graphical additions add to the game, literally just turn off the HUD and wonder around the world. I can't play it at max settings though which is surprising without it dipping into the 20fps range but the kicker is because of /drumroll, the shadow setting, turn it to normal and everything is smooth again at 60+ Fps goodness.
I thought the biggest hit would be ambient occlusion or AA, maybe even volumetric fog but it's shadows unless it's just really not working right. Also that fancy rain tech is kinda laughable when the rain when it touches the ground is just a texture itself, wasted opportunity for volumetric rainfall on terrain ubisoft!
But enjoying it again, almost back up to where I was on the 360 version and my ship is miles ahead. I notice some of the things I could do in missions on the 360, it didn't allow me to do it on pc. One of the early missions on 360 let me roam a certain entire island without needing to be near the npc but the pc version didn't so I had to gather everything afterwards because it wanted to desynchronise my character.
Other then that, games eye candy on my 60inch, ubisoft really puts some love into pc ports lately.