I'm actually a huge H2G2(and Dirk Gently, and Last Chance to See) fan and really enjoyed the movie.
Mos Def was brilliant and I fell in love with Trillian, those eyes....
The 'Cotton' scene had me laughing for ages, very clever, especially the puke, haha.
Douglas himself wrote the script and had a huge roll in the creation of it, although he was unfortunately not around for the filming and editing which is a shame.
I have only one criticism, the use of an 'unknown' director who had never shot a feature movie before.... the actors tended to mumble which made it kinda hard to follow at times and was something the director should have addressed during filming and post production.
Actually two, Zaphod's second head should have been as per original, wouldn't have been very difficult to do with today's computers.
Omaroo, if you're interested in the 2005 radio plays, the Tertiary, Quandary and Quintessential Phases, they are available for download:
http://www.sadena.com/hh/
They feature all the original cast(except for those that have sadly passed away) and many guest appearances.
They are also available as Torrents with higher bitrates for better audio quality -probably ripped from the CD's.(which you might find at your local library)
Anyway, getting way OT.....