I'd never heard of this drama series, but an article on The Register (called Why British TV drama is crap) put me on the scent.

Not entirely sure how good The Reg's TV advice is, I downloaded it, and got totally gripped by it.
I watched all 4 Seasons, and enjoyed every minute.

In fact, I've been recommending it to everyone, and everyone I've recommended it to has liked it.

I have just ordered the Series 1-4 DVD box set from Amazon as well - it was that good, that I thought it deserved a permanent place in my DVD collection.

I'll advise you to watch it too. Order the box set today.