It's incredibly interactive. I randomly walked into a cafe sat down by pressing Y and my partner sat opposite me. And all I did was press X and we'll start talking about a case. Outside the cafe I was in it was raining and you can hear the rain running down the windows as well as seeing it . Such brilliant graphics and sound-effects. And the facial animation is amazing.
As for the detective side of the game its the best out there in terms of detective work. So indepth! At times it can get repetitive but that doesn't mean its a bad thing; having to do the same process with collecting evidence, avoids frustration. There are 40 side missions were you respond to dispatch by pressing A whilst driving along, thats quite a lot of missions bearing in mind that is 40 completely unique side missions which we'll keep you busy for hours.
The whole concept of going Detective instead of being a criminal doing as you want around a city was a pretty risky approach to introduce to the gaming market. But they've succeeded very well, simply because it is Rockstar and they are always setting a very high standard, no matter what concept they choose to create in their open-world games.. So role on GTA5!