from my 15 hours with this game, I definitely like the story missions the least.
I wouldnt say they are terrible, but they are underwhelming, the story missions are usually divided in 2 parts, one part "thief" gameplay, one part more streamlined and linear.
what I really love about the game are the side missions though, they come in different sizes, there are big client side missions with own areas, there are medium side missions that you get from your handler who tells you to break in somwewhere, and then there are the tons of mini side missions you get witthout any quest at all, you can break in at so many random windows, you overhear conversations that give you hints where special loot can be found, there are different chain quets that dont give you quets in your log at all, they are just pieces of paper with instructiony you find, no quest marker or anything.
I really love how they did the city, its so much fun to move around in it and look for access points to places where you want to go, there are some really good puzzles involved, shooting tiniy buttons from different angles, jumping and climbing from roof to roof.
I think they city is definitely my favourite thing in the game so far, I spent at least 5 to 7 hours only in the city.