Truth be Told
I got a book in the mail the other day from a publisher in the UK. It's a thick, nearly 600-page hard cover about the show. Been flipping through it and it's a very impressive book. Lots of interviews with Wire actors, crew, producers, you name it. The most interesting part of the book is a long foreword by David Simon which sets the context for the show among television cop shows as well as in his own career as a journalist. I had not read much prose by Simon and it's very well written and elucidates all the themes and intentions very clearly. Also an 18-page interview with Simon by Nick Hornby.
The main reason to get this would be for the interviews and the hundreds of photos interspersed throughout. It's really a good addendum to the show with the interviews really shining a light on the myraid aspects of the show. It's got summaries of all the episodes, through from what I read, they're not always carefully put together - the summary for Season 4, episode 1 for example, inexplicably failed to mention the murder of Lex. But overall, it's a great resource for a Wire fan.