Two seasons, 3 episodes per season that are 90 minutes each. Last episode aired today and I just finished watching it. I have to say, it's probably the best TV Series I've ever seen, not that I watch a lot. Actors are quite fantastic and it's a very great change of pace to the crime drama garbage like CSI and whatnot.
Not going to post any spoilers since it's a Crime Drama, and spoilers basically ruin everything, but the show is just Sherlock Holmes based in modern times.