oh god.ill give them props for the good storylines they've adapted or made better. Terminus, Claimers and Hershel's Farm buttt Gov/Michonne, Billy/Ben, Maggie attempted suicide and carol/tyreese are four of probably the darkest stroylines that got cut/warped.
For Mich/gov- I mean if you've read the comics you know exactly what i'm talking about. AMC just simply could/would not do that full arc.
BillyBen- yes, it was adapted but it was super more twisted in the comics because of the Carl/Andrea relationship that develops further on. Though I did feel for Carol
Maggie- mannnnnn this would have been good. I know we got the Abe/Glenn conflict over whether to move on or not in the show, but watching the bubbly love happy girl lose her entire family, and then give up was heart breaking. And when Abe says what needs to be done after they find her hanging, NOBODY will listen to him and it causes a rift between Abe/Rick (IIRC is around when he begs Rosita not to let him kill again, and mentions being close to killing rick)
Carol/Tyreese- crazy ass white women.. but seriously carol lost touch with reality which was a nice way of showing that not everyone would survive, not just physically but mentally too.
TL;DR- The comics seem to go darker with rape, torture, suicide, and child-murder being more frequent. The shows, for their reasons ("We CAN'T show that" or "why the hell WOULD we show that") decides to take things down different paths for some scenarios, or follow the comics for others.