Somebody recommended buying the DVD of the British show "The Hitchhikers Guide to the Galaxy" instead of seeing the new movie. They were right. Not a big budget but it stayed faithful to Adamses story and lines, which is what makes it funny and interesting, the whole point of the stories. Read transcripts and saw trailers of the new HHGTG and noticed most of the humor was sucked out of it.
I rented the British version of "The Hitchhikers Guide to the Galaxy" a while ago. It has "Dr. Who" production values, but was true to the book. If the story is funny enough (and it is), you can overlook the $25 special effects.