Finished it today.. Bought it on Saturday, and haven't been playing really hard.
I think the thing is that the side missions mostly sucked balls, so I haven't really done any of them except for a few. The story missions are mostly ok, but I really miss an option to go on a lot more heists instead of the 3 or 4 in the storyline. And it sucks that you have to start a new game to be able to try out different options, meaning that to be able to try out the other solution on the final heist requires a lot of bullshit playtime instead of just allowing the player to simply restart that heist.
Hopefully MP is good, because SP was pretty thin and not really a 9/10.