I don't know if I like some of the design choices, such as how they're doing Zophod's extra head, or Marvin's appearance, or the Heart of Gold, which was supposed to be shaped like a running shoe. Still, the production values look a lot better than the old TV show. It's hard to tell about the delivery of the jokes--could be the way that it's cropped for the trailer.
From what I've heard, this movie is just going to be the first book: The vogons, the heart of gold, the mageratheans, the telephone sanitizer people (I forget their name). It definitely sounds like they're setting it up for a sequel if not a trilogy.
For anyone who's interested, here's a review of an early screening from an obviously biased viewer:
http://www.aintitcoolnews.com/display.cgi?id=19282