I like the setback cards. They are a risk that you need to manage, like building up a bit of mobility against the movement ones, and spreading out disks in depth 3 so you don't get messed up by the "depth 3 card is replaced" one. They do make the game more difficult, and not playing with them is certainly an option to reduce difficulty, as is looking at which 4 setback cards you got, so you can prepare accordingly. A generic "they are absolute crap"? I disagree.
I like the setback cards. They are a risk that you need to manage, like building up a bit of mobility against the movement ones, and spreading out disks in depth 3 so you don't get messed up by the "depth 3 card is replaced" one. They do make the game more difficult, and not playing with them is certainly an option to reduce difficulty, as is looking at which 4 setback cards you got, so you can prepare accordingly. A generic "they are absolute crap"? I disagree.
I go into more detail about why I don't like the coop implementation in my review