PLayed this for few hours yesterday. Got through training and traffic division. Now i'm with homicide. I ended up leaving audio/visual clues on because otherwise it would be near impossible to find some evidence without them. Also, although the story progression is very linear, it seems like mission progression has some branching parts - get to the scene of domestic disturbance quick enough and you can catch the attackers. In the end you can still beat the cases, but branching does help with the narrative.
V/A and animations are best i've ever seen. Writing is noire campy, but fantastically so. Most of the time it really feels like you're watching a movie. Basically it's another win for rockstar.