I've been playing the 360 version in 720p mode. There is minor tearing. It seemed more apparent earlier on in the game, right after I got into the open world. I have no idea if it had to do with the game getting warmed up, loading, or my eyes adjusting to it, but by the end of my session tonite, I wasn't noticing it much, if at all.
The framerate isn't perfect, but it's close enough. You sometimes get the odd slowdown or hitch when it goes into a cinematic cum inducing view. Nothing that affects gameplay.
The game looks fantastic. Total package, it might be the best looking game I've seen. Now, taken on their own as individual elements, the lighting, models, environments and clothes probably aren't the best, but as a total package, they come together at least as good as the best I've seen. It also has some of the nicest, most realistic ragdoll I've seen. That means that a lot of the time it is pretty subtle, but you get special ragdoll goodness when you, say, fall off a building, or throw a guard off a building.
But yeah, there are technical flaws, but if you complained about most of them, even the tearing, you'd be nitpicking. It's a visual 10, both for technical reasons and consistent OMG design.