For those in the UK that missed it, i.e. people without insomnia and the patience to second guess C4's astonishingly evil/random scheduling in order to record it, this is one of the best programmes ever made - period.
One of the first (to me anyway) shows that allowed characters to develop over the entire series it allowed all to shine and is a far cry from the shiny CSI nonsense...
It requires work on behalf of the viewer as the dialogue is real and it assumes that you have intelligence enough to follow it.
As for extras, maybe a few would have been nice, but I personally am not fussed and you wont be bothered as the programme itself rocks...