One of the concerns (ok, the only concern) I had about GTAV was would having 3 protagonists impact my ability to become engaged in the game. And I can report that my concern has been validated. Maybe part of the problem is that Michael's complete impotence and ineffectualness as a man/father/husband doesn't make him particularly compelling to play. GTA characters while wildly flawed are usually cool. Michael is a colossal loser. Generally in a game like this, where you get to make choices, the character I play at some point reflects what I want them to be. But with this system, I don't feel particularly driven to care about those choices.
What I noticed in particular is that in previous GTA's I usually would force myself to stop doing mainline story missions and take time to explore and do other things. This time it's the opposite and I'm forcing myself to do the mainline story missions instead of just driving around and goofing off. I like playing tennis. I don't like getting the feel of a char and then having to change to a different one.
I would have preferred if you had to choose your char at the beginning of a new game, and then stick with it all the way through. Encouraging replays.
Fortunately the gameplay itself is fun enough and I'm hoping at some point something will click and I'll enjoy having access to all 3 chars, but for now I'm enjoying playing, but not as engaged as I usually am with GTA games.