I really didn't think I would like the Wire when I first heard about it, but I gave it a try earlier this year and ended up watching all 5 series in little more than a month.
I've also just finished watching a mini-series called Generation Kill by the people who made the wire, which I found to be pretty good, it's about the first few weeks of the Iraq war. Bit of a shame it was only 7 episodes though.
I seem to be watching more US shows than British ones recently what with those two plus Dexter, Heroes, Prison Break, 24 etc...