Too much soap style drama, filler episodes and sloppy execution of many ideas and concepts. Plenty of lazy writing when it comes characters deaths too. There have been some fantastic episodes but as coherent and solid seasons they never seem to gel together that well. Darryl and Carrol characters have been pretty good additions/improvements to the comic storyline who are at least midly consistent and relatively tantrum free. There have also been plenty of lemon actors with all the minor roles that were needed to add to the body count of the show too.
Still seem to be plenty of folks enjoying the show so who am I to say otherwise but for moi it's relegated to "watch it when it's free on Netflix" league now as I've been watching it for the sake of it hoping it will get better for a long time. Maybe I expected a little too much, hoping for that Battlestar Galactica style show with zombies with good story arcs and character developments which would still keep the FX budget relatively low. Closest I've come so far is reading World War Z.