I disagree with Bryony - there isn't enough zombie fights - It's little short of a Soap Opera. There was one episode in the second season where there was ONE zombie in the whole show. I read the comics, which really push the 'what would you do if there were no longer rules of society' barrow. I find the tv show a little too sanitised and they've taken out the moral ambiguity. It just the good guys are good.
Third season was just a big yawnfest - that said, I guess we'll watch the 4th on dvd because there is a big nothing else to watch. We are on a scout for some new series to get into...