Problem to me is that in V, missions relating to the thugs, robbers, cartel, gangs and the usual glamor of criminal life simply isn't fun When compared to the mission branch and heists given by the FIB.
For example it still feels forced to me whenever the game asks me to shoot more Ballas, the last one in the forest in particular was weirder than the intrusion of government agents throughout the plot.
And I'm saying this while keeping within the context of V's story missions, not to compare with what worked better in the past.
I agree that too much emphasis was placed on the FIB side and not the IAA; the United Liberty Paper Contact's role from office desk mission giver to on-the terrain foot soldier was badly done.
I was actually surprised and glad to see that Martin Madrazo was Not one of the game's leading antagonist. It plays against type and expectations. Madrazo wanted what he is owed, and once he is given, he lets the protagonist be.
How many times before have we gone through with these drug lords or kingpin who annoys and pesters the protagonist throughout the game, it's cliché and getting old, they always shout and act mean and in the end the protagonist still ends up shooting them in the face. Granted the FIB agents in V haven't exactly been any more subtle, but at least the uniform is different, it helps to have a bit of additional flavor.
Frankly though, my initial expectations of V pre-release was that there wasn't going to be any of the standard story and antagonists.
It was just going to be about heists and making money by all means. The three playable characters were to be their own antagonist when the time is right, when the stakes is too high, and the taste of sharing too dull.
I have no problems with such missions, whether you work for FIB or not.
All I need some interesting options and non-scripted GTA action to play ANY mission, irrespective of what's popular.
GTA V has managed to offer the variety and a beautiful map, but it still hasn't yet managed to get rid of "go there, do X and scripted trigger of events" approach in their appeal.
It hurts the replay ability a lot.
Also, I find many missions could have been less annoying and more challenging with one protagnist than switching back and forth.
Hopefully the next entry in four/five years will finally allow for some free-form method of play.
The character switch has potential, they may hopefully have already made improvements for the DLC.