Adult Swim has added a number of new shows in the last two years, and people have had all sorts of reactions. Regardless of whatever reaction a person may have to Metalocalypse, you have to admit that it will get your attention once or twice.
Without parroting the same praise others have given the show, I'll say that the reason it's so intensely hilarious is because it takes five very well defined characters illustrative of classic metal personalities and brings them down to earth, readily accessible, and just waiting to screw up horribly in everything else they do. No matter how well or ill intended they are in their non-metal deeds, they invariably amplify the horror of the every day human experience. When we sit down and watch, we're just dying to see what the death-toll will be.
Some people have said that the humor in Metalocalypse is "too simple", or "too tasteless"; I can't really argue much with the latter because gore is a running gag, but I'd hardly dismiss it as "simple". Granted, unless you're aware of metal archetypes and racial stereotypes of Scandinavians, you're going to miss a lot of the "inside jokes" and things may get boring. Nevertheless, if you watch from the beginning and keep each previous episode in mind as you watch the next, it'll all make sense. That's one of the reasons I'm absolutely enamored with Metalocalypse. The prevalent attitude coming from its creators is not smug or exclusive or stuck-up, and it doesn't feel like they're trying too hard to be funny. Everything strikes me as being quite innate and not at all forced or deliberate.
If you ask me, metal itself is a pretty pretentious genre. Like gangsta rap, metal personalities are almost invariably malignant. Luminaries of either genre have always portrayed themselves as infallible gods who know no wrong, and can do no wrong. A quick study of any celebrity culture in any country indicates that so many of these people are terminally narcissistic and histrionic, ready to take full advantage of us little people. Rather than fume while resenting it, we can make fun of them and remind them that they still use toilets and make stupid mistakes.
Many people have compared Metalocalypse to "This Is Spinal Tap", and I can see that. I can sooner see a comparison to "CB4", though. I would've loved it if some genius had managed to make CB4 into a series on Adult Swim. Same concept, slightly different details. Point being, it's a great deal of fun to plot through the "real, dumb lives" of people who believe themselves to be living gods.
In any case, I absolutely love the show and measure my weeks in terms of Fix premieres and Sunday night airings. This is the best new show on the network, and I hope its creators take full license when creating more episodes. There is a host of potential in Metalocalypse because metal itself will never go away, nor will the personalities behind it. If I don't get at least another season or two, I'll just develop dysthymia.