While I can't recall all the other seasons in detail, Flesh and Blood is definitely the best of the 4. They managed a well done 360 on the predictability factor by throwing a solid curveball. Some of the characters and subplots were interesting (and despicable but in a well placed sort of way). The show definitely suffers from some instances of "hard to believe moments" in the dynamics of characters after certain interactions. There were some deaths which seemed entirely unfeasible as well. Also, it suffers from the cliched and silly common sense moments ("Let's split up" "We got him, but let's not sustain the attack!"). Still, it was more believable than the previous seasons.
This show contains the most gruesome and realistic gore I have ever seen. It is more violent than the previous seasons, GoT, AHS, TWD...etc. It is astonishingly brutal and believable; everything from decapitations, dismemberments, and disembowelments. It's not limited to blood and guts; every major organ is depicted in graphic detail. The level of details in some scenes are even sickening. (ex: colon squeeze).
I suppose it's a bragging right to be the king of gore, but too many shows these days try to out-shock the last. In 2011 GoT revolutionized TV with its shock value; showing the darkest depths of human depravity. Nowadays, nearly every show has attempted to show the same level of depravity using regular, relatable people. Slasher doesn't bring a unique level of shock to the table, only because those things have all been done time and time again. But, they managed to pull it off better than AHS did.
Overall, it is an entertaining ultra-gory anthology -- well worth the watch.