Although unevenly paced at points, when Beavis and Butt-Head is funny, it is VERY funny. Mike Judge has a great ability to frequently make juvenile humour seem like sophisticated wit and even if it is an example of dragging a loose plot beyond what it should be, you can settle in with the assurance that a really funny joke is around the corner.
The set-up of the plot is great, and a brilliant excuse to bring its characters into the present day, and the voice case gives it their all and then some (special shout out to a brilliantly dead-pan Gary Cole).