I'm not sure how realistic it is but it's certainly made me want to be a big city cop (although without the corruption). The relations between the characters are touching, the show is intense, gripping and the characters extremely likeable. Seeing the way the Strike Team are like brothers makes me crave being part of such a close-knit team who are always watching out for eachother. You also end up loving and supporting a team of corrupt cops who you should see as heartless criminals, but you can't because they're deep-down nice guys looking out for their families. This odd combination is similar to that in 'Dexter'.
There are also various sub-plots such as Acevada's political campaign, Vic's marriage breaking down, Julian's conflict between his strong Christian views and his homosexuality. This show does not get for one second boring, unlike CSI which is 95% police procedure which can get a little dull and repetitive, The Shield has gripping characters and a great storyline, a must watch!