I'm coming up to the end of series 1 on DVD. It's pretty good. You can see the similarities to The Wire - the detectives slagging each other, the tight resources, their interaction with the public/public perception of the police and of course, Baltimore. Spoiler: The newbie detective (Bayliss) reminds me of Dutch from The Shield. Some familiar faces in there as well. Robin Williams guest starring was a bit odd. Thus far it's mostly focused on the police rather then the police/dealers/city officials/community, etc.
By the way, it was on RTE 1 last night at 1:35am or some stupid hour. I didn't watch it, but ended up reading a spoiler in the episode summary. Ah well.