These guys, Adam and Jamie are just great. The whole show operates on two simple premises: 1) test common myths and see if they are actually true, and 2) if they aren't true, see what extreme conditions would make them true. The first one is usually easy enough to test, and I'd guess that 95% of the myths turn out to be complete and utter nonsense. The second one usually involves making things explode, break in spectacular fashion, or a little of both.
It's funny though, the show has changed over the years. Somewhere along the line, they ran out of myths... so now they seem to do more testing of "could thing things you saw in the movies really happen? Or did they just look good on film?" These are entertaining, but they get old, just like everything else.
One other interesting thing I found out is that Adam and Jamie really aren't friends, though you wouldn't believe that from watching the show. ['MythBusters' Friendship Only Gadget-Deep - AP 4/26/2005] Apparently Jamie didn't even go to Adam's wedding because he "didn't want to". Touching. Though you can definitely tell that often they get quite frustrated with each other on the show, now I know that it's completely real.
It used to be just the two of them, but now the cast has "expanded" to include their understudies or "Mythterns" as they are often called. What a waste... all they get are the dumb myths that Adam and Jamie are too good to deal with. I think it hit rock bottom for me when they tested a myth of whether plants grow better when you talk to them than when you don't. I mean honestly, booooooooogus. I think the page at jumptheshark.com summarizes much of what I'm talking about.
I think it's the same problem of driving good shows into the ground. Like the first Who Wants to be a Millionaire prime-time series (the one hosted by Regis)... that was exciting when they had it on for limited spans of time, until they started showing it 4 nights a week and everyone got sick of it. Why can't people leave well-enough alone?