The series gets surprisingly good. It helps that they got most of the movie voice cast. They also sneak some little science lessons in very clever ways - in one recent episode, they're trying to figure out what rocks the Grunkle ate to produce steel, and their attempts include a neat little lesson in what happens when you heat up various types of stone (she eats sandstone and produces glass, for example).

The trailer for the second movie looks pretty good, and I am optimistic.