Great series, great price!
Next cheapest is £8.85 at Zavvi.
I think this review from an Amazon customer sums the show up quite well:
One year in the life of New York's emergency services - focus here on the police, paramedics and firefighters of the 3-11.00pm shift. Prepare at once to be swept away by the pace, depth, sheer realism of it all. The first few episodes are a bit hard to take in with so much happening, so many people involved. Soon the central characters become more familiar - all totally believable and extremely well acted.
Each episode provides much food for thought and is completely involving - viewers destined for laughter, tears, at times unbearable tension and the occasional very real shock. Here there is no such thing as an ordinary day, especially with so many guns around.