I've covered this show a few times at work now and find that I'm completely hooked. I think it's at least as much having the right host as subject matter. I don't know where Discovery Channel finds these guys, but they've really got a knack for engaging, charismatic nerds (see also "Mythbusters")
Granted, I really didn't need to see Mike Rowe hold a cup while a pig farmer procured genetic matter from a boar, but I've yet to see a guy with as good a sense of humor about standing knee deep in raw sewage.
If I remember that the show is on, or flip by it, sometimes I'll watch it. The one where he was with the Exterminators was great, as was the Ostrich farm. I don't know how this guy manages to stay as enthusiastic as he does for these jobs :)
My wife and I took my nephew (5 yrs) and niece (7yrs) to see it on Thursday. My wife was highly skeptical going in that they would "do it right". She was impressed that it stuck to the book as well as it did.