Okay, so the shooting feels like Saint's Row to me, which is good. Precise targeting works well. Enemy damage animations looked a little canned to me, but Nathan looks fabulous. AI is spotty. I've held back a couple of times to see if they'll come at me and try to flank, but I haven't seen anything like that so far.
The game is beautiful and sounds gorgeous. I can hear the birds in the distance even while I'm busting caps on the pirates. I seem to run out of ammo pretty quickly which has caused me to need to run into a firefight empty-handed, beat the snot out of some guy and take his weapon. The combat animations look good, but there's still a sense that they aren't actually touching each other.
When you do nothing, Nathan hunkers down in a squat, looking bored. The water is very nice, although it doesn't seem to flow around Nathan, but he does get wet, which is cool. No problems with the platforming bits at all.
Edit: The screen turns gray as you take damage so by the time you're dead it's all in a fuzzy black and white.