I've read this series at least a half-a-dozen times.

Mos Def was HORRIBLE. I certainly don't remember the part where Ford Prefect gets a labotomy and mumbles throughout the book. In fact, Ford had no presence in this movie whatsoever! In the book he's witty, charming, mischievous. In the movie, he's a zombie. The scene where he's scarfing down beer at the beginning isn't even explained! It makes no sense without explaining that he's trying to minimize the effects of hitchhiking.

Zooey feels like she's reciting her lines.

Arthur is just some guy in this story who makes funny faces once in awhile.

Slartibartfast obviously had the same acting coach as Mos Def since they were basically the same character (mumbling, weird pauses..).

Kudos to Sam Rockwell as I kinda liked his Zaphod, but even that character fell apart at the end.

The ending. Whoah boy! Talk about dumbing the movie down for mass consumption and completely screwing up the events in the books. So I guess there's not going to be a prehistoric earth in the second movie because SURPRISE Earth was completely restored and everyone lived happily ever after.

Blech.

I keep hearing "True to the spirit of Douglas Adams!" Maybe the guide, the heart of gold and the parts that didn't have actors in it.

Try the BBC version. Sure, it didn't have the special effects budget, but it retained the story and the "spirit of Douglas Adams" much better.