It's pretty much exactly what I expected, which is to say that despite the setting it has more in common with Assassin's Creed than GTA. I haven't gotten too far into the campaign yet, since I will probably restart the game on Tuesday when my legit copy unlocks. I tend to get distracted by side-missions in sandbox games anyway.
I will say that the Person of Interest-ish crime-about-to-happen-somewhere notifications are getting to be almost as annoying as getting phone calls from assholes wanting to play darts in GTA IV. I was responding to most of them at first, but now I just ignore them all. My vigilante meter was maxed out and I've got enough skill points now that I can probably buy every single skill that unlocks in tier 2, and I still haven't even started the campaign really. Kind of feels like cheating to get that much xp.
The only other thing really bugging me so far is that the cops seem to be omniscient at times. Escaping from them can be a real chore even if you use hacking to wreck their cars. You cannot hide in my experience, which makes escaping on foot nigh-impossible. You simply have to outrun them and then get outside their search radius.
I'm having a hard time getting used to the controls too. Driving anywhere fast is not an easy task to say the least, and the mouse controls are pretty floaty even with smoothing shut off. You can switch from gamepad to mouse seamlessly, but I just don't bother because it's not any easier for me to aim my gun with the mouse.
Performance is solid and with everything set to Ultra except textures (I only have 2GB VRAM which is unfortunately not enough for 4k textures) it really looks nice. That's with AMD; Nvidia apparently requires beta drivers to run the game decently, and even then people seem to be complaining about frequent chugging that I very rarely see happen. You also need a pretty hefty CPU as well, as the game is not solely GPU-bound by any means.
ultra textures claim they need 3gb of video memory which seems a bit ridiculous
Not ridiculous at all, unfortunately, for those of us with 2GB cards. Ultra textures are 4096x4096 which simply doesn't work for an open-world game at 1080p+ resolutions on a 2GB VRAM GPU. You can see the same thing happen if you mod Skyrim with 4k textures everywhere.