I think you have to go into it knowing it's not actually a sandbox, and there is expository cutscenes, rather than in game events. (However the style and marketing should not be so vague that anyone should ever have to say that, and it is a definite minus to the game) It's a straight story that will last about 12 hours and does involve a lot of driving about and waiting. What worked for me was whilst washing a window is a boring task, it is in anticipation of something more interesting happening. The people you are beating up in some cases it is for a very good, or in one case very satisfying and corny 'mafia movie 101' reason.
It's an ideal rental for any fans of mob stories, it's a slow burn game and it is one that will wither endeer itself to you or make you angry and frustrated at the pace, the cars and the 'day job' aspect.
By the way try getting a car to 125 mph in the game, that's a challenge!