Nice.I tried not to rush, do a few side missions when available etc and I would say? Maybe more?3 hours
You could have driven to the location I'm talking about at any point, but I pretty much stuck to the City when playing as Michael / Franklin. I took a little detour up a mountain into the sticks (where the cable car is) and it was raining and I couldn't see shit.
I think it's the scenery, plus the massive change in character and the situations you are thrown in as Trevor. The game is basically saying to you, "OK you have shit pretty much down now, lets get down to business."
remember reading the interview from Leslie Benzies about how they wanted to really throw you into the things more quickly in V than IV, so a few hours sounds good. A lot of impressions I've been reading are saying that the story picks up quickly.