The show itself is superb, it's simple gag-heavy and very well produced. If you intend to purchase this DVD box-set then you probably already know this, having seen it on TV. However the DVD itself offers little apart from the series itself. It has a few extras, but not many. A few audio commentaries (not one per episode as you would expect) and a behind the scenes film, which was clearly done by someone who was bored during the filming and had little else to do.
In short, the show itself is superb but the DVDs themselves add little to the experience. However the price makes it worth a purchase, as you can't go wrong for a tenner.