The missions were very solid and varied, probably the most varied in a game of this genre i've played.
They were more linear than they should've been, but that's a very common problem among all open world crime games.
There are a multitude of problems with this game, but i feel that towering over all of them, for me, was the inherent fragility of the characters.
It's simply a slap in the face of mayhem and exploration, when your character dies at the first fart blown in his general direction, and you respawn 40 miles away at the nearest hospital.
Then of course there are the plot problems, the obsolete "garage" system, the controls issues and a host of other elements, but the one above was the main reason why after i finished the story, i put down the game waiting for a moddable PC version to come out.
Overall, however, it's a great game in my book.
Honestly, open world games are becoming bigger and bigger and I don't think it's a good thing.
I'd rather have a San Andreas sized map (which was big enough) full of detail and interiors than a huge map without enterable buildings with places I'll never see in my life because the map is so huge.
I also disagree with this mentality.
Some games benefit from a smaller map, but i think GTA is not one of them.
To drive and, especially, fly around you need a pretty big map, lest you get the feeling of being trapped inside a tiny box.
In GTA San Andreas they got around it by simply having a ridiculously short draw distance.
Also this obsession to have "interiors" in a game which main activity is meant to be high speed driving, and vehicle use in general, i'll never understand.
So you can enter in a bunch of empty hallways and rooms, now what?
GTA is not really a Hitman game.