How's the performance on ps3?
I have only played about an hour so far, so I can't say how the performance is long term, but I think I have a pretty good feel for it. Out in the world it seems okay. It isn't super smooth by any stretch, but it isn't bad either. I would say that it is trying to maintain 30fps, but not quite getting there most of the time, or fluctuating just enough that is noticeable. The same can be said for the open sea ship battles, trying for 30, not quite maintaining it, but not terrible.
Now, in city is a whole other story. In Havana I would be shocked if the framerate ever maintains 30 for more than a few seconds. It is really choppy and can get unplayable at times. I'm not talking "oh man, 25fps, that is unplayable" either. At the end of the first mission in Havana I had to escape the area and the entire time the framerate was easily sub 20, and there were a few times that I wouldn't be shocked if someone told me it entered single digits. It was so bad that I was having a hard time navigating rooftops.
Even still, it is a very playable game outside of the city, and it looks pretty damn good for a current gen game as well. I would absolutely hold out for the next gen version, or do what I did and go the upgrade path. The only reason I even have the PS3 version is because it was basically free with the $50 PSN promotion.