What can you say about this show and Vic Mackey and his unorthodox strike team that hasnt already been said.
I have watched alot of tv shows (sopranos, the wire, Oz etc) and the shield eclipses them all. No tv show i've seen before or since grabs you by the throat and slaps you around whilst you watch it - the shield does.
The writing in this show is top notch bordering on genius, every episode is a story in its own right but the overriding arch story of the strike team and their past endeavours catching up with them is always going on throughout, from the unforgettable epsiode one. The characters in this show are of course wonderful and in Vic Mackey, Shane Vandrell, Dutch and Claudette you have 4 of the greatest tv characters ever created, you will be gripped and taken in by all of them.
The other thing the shield has over its elite competitors is IMO - not only the greatest tv tale ever woven(across 7 seasons) but that is doesnt have one weak season. What i mean by that is I couldnt even seperate one season and say it was better than another, they are all equally sublime and brilliant.
Just do yourself a favour and watch this unforgettable show.