I have to admit I have never read the comic so I cannot comment, but having said that some things - maybe even major things will not translate to a TV show for whatever reason...budget, schedule, ratings, censors, etc etc.
Obviously there is some piss poor writing going on, but I have sustained my disbelief and have bought into the world they created for AMC. At first I was quite skeptical as I was not digging Andrew Lincoln as an actor but he has since grown on me - but ever since he had his 'Brad Pitt - that's not my wife's head in the box' moment of hysteria, they need to get rid of this Margot Kidder crazy spell.
I think the 12-13 episode arc is perfect for TV, as it allows more thought to go into story progression. Anything more or less tends to be super fast or drag on endlessly. For example, last season or Breaking Bad's 8 episode arc was not working and felt out of place for that show. But even shows with good creative teams, its a lot to ask for a full season above 12-13 episodes - not every one can be 'good' and shows start to repeat themselves and get into cliche. It's like watching a cop show - then eventually they run out of storylines and the 'Asian gang episode' pops up.
For TWD, most of the core characters have been killed off, there was a lot of tension within the group so the writers had 'more to work with' - and they were all in the same place and they had time to grow. It's not 'choppy' like OK, lets go to Woodbury, then Ok let's go to Tyrese' group in the woods, lets go to Andrea and Michonne, etc. They have also changed the show runners twice now, so that has a lot to do with the writing quality - hence as I mentioned in a previous post the increase in the gore factor as seasons progressed.
That's my two bits for now - well at least Justified is still good, and coming into it's own.