Turn off VSYNC and turn on Hardware Cursor, it will remove the mouse acceleration. The game plays quite well with a k&m, although, like in TW2, CDPR does like designing things to be gamepad friendly. Probably because they're Polish.
It is also capped at 60 FPS by default but you can set that to unlimited (which is oddly placed on the left side of the scale, but I guess that makes sense as it would be the "off" position).
I am running with almost everything turned on and on ultra on my R9 290, it was at 35FPS at worst and 60 at best until I turned vegetatino distance down to high (didn't notice any real difference for the most part aside from an improvement in FPS) and grass density down to high b/c i don't really care about grass and the vegetation & grass quality is the weakest part of the graphics. FPS is generally around 60 now. (I also have hairworks turned off because I don't have an NVIDIA card and it is a massive performance hit even for 970s, I turned both blur and motion blur off and depth of field off too).
The game looks stunning so far, the "cartoony colourfulness" people were complaining about is largely an effect of the lighting during sunny days, even at 1PM in light rain everything got a lot darker (also for some reason 4am is sunrise, and the sun actually starts rising before that). Sound and animation (including faces!) quality are top notch though. Gameplay is very much an improved version of TW2, I still end up dodging a long but there is dodging and rolling, not just rolling). A lot of stuff still is colourful, especially clothing, but for the most part it is quite nice and as I said changes a lot during different weather. Medieval clothing was actually very garishly dyed in reality too.
The tutorial is actually extremely long, it seems like the entire first area is still tutorial land, I didn't import my save yet and the game still hasn't asked me about stuff that happened in previous games in lieu of importing a save.