Well, 14 hours..starting Vice Cases (well, "starting" since I already did 'The Naked City'-DLC, while I was in Homicide); and Like it more, the more I play it.
I still haven't jumped directly intro free-roam, except to just look for a few cars and badges to add to the collection, but the overall game is a mix of two of my favorites games...
Chases (on-foot/rooftops): Assassin's Creed II/Brotherhood
Simple and direct to the point. With a lots of turns, stairs, jumping, poles, people walking by. Some even have destructible environments which add to the tension.
Investigation/interrogations: Phoenix Wright/Ace Attorney Investigations
Also simple, but still interesting. During the investigations there may be a lot of items on screen, but only some are actually relevant to the case. Then the ones you question are either always involved or the actual criminals. You have to keep an eye out for their expressions and gestures to get to know where and when they lie.
Also some things that remind me of Heavy Rain (looking at things/items), shooting and driving feels like Grand Theft Auto IV, and a little of Red Dead Redemption (like being a relatively good-guy and not a mass--murderer that can destroy the entire city and shoot/kill everyone...without actual consequences)
There's also the open-world, which lets you takes on simple missions of chasing/shooting criminals, collecting badges and film-reels hidden through the city, newspapers through the cases to expand the story a little more, different types of cars to keep an eye out..and the map's huge, so there's usually something new to see and look around.
Plus the whole 40s setting, music, clothing, Black Dahlia references, corruption, etc... the amazing visuals and level of detail, the facial animations, acting, dialogs...
If things manage to continue the same, will definitely be one of my favorites games this year.
NOTE:
Xbox 360 version, by the way!
Disc 1: Ended around the 6.5 hours mark
Disc 2: Still on it. Currently at 14 hours