Oz is a very different kind of TV show. I started watching it after The Wire, and struggled to get into it. It's deliberately theatrical - Harold Perrineau narrates and breaks the fourth wall and has monologues - which can be a little disconcerting. And it is 12 years old, so it looks a bit cheap.
But I will get around to watching it. Maybe once I've finished with Deadwood, which is fucking amazing by the way.