It is a great series. Maybe the best thing Vic and Bob have done, although Bang! Bang! is probably the most quintessential of their shows. Catterick, as a sitcom, was new grounds for them.
Vic Reeves' two main characters here are amazingly funny, even better than they were in Bang! Bang!. As an American, D.I. Fowler's accent is one of the funniest American accents I've ever heard. It's just ridiculous. Bob's main character, Carl, is very low key, but still provides many great laughs. Vic's Chris Palmer is also extremely funny.
The supporting cast is great. Matt Lucas, Morweena Banks and especiallly Reece Shearsmith all are at their best here. Tim Healy's stories about his "cold" wife are also a highlight of the show. The songs in it are great as well, and make for some really interesting, almost Magnolia-like scenes. Lastly, I think it worked really well as a single series, although I wouldn't mind seeing more, I think the story was done and told very well. Highly recommended to anyone who hasn't seen this yet, and as others have said, you might not have to love their other shows to really enjoy this.