Hitchhiker's Guide to the Galaxy (2005)
Saw this in the theatre, for a change. Haven't been to the theatre in so long I almost didn't mind that we'd waited so long that it was in the cramped, standard-seating theatre (that is, not the good clean stadium seating theatre).
While the movie was well put together, it was a little disappointing.
I found myself laughing at bits, and chuckling under my breath at some of the bits that were as if read directly from the books. I can see where it'd be hard to introduce some of that interrogative into the film.
The bits of film that were presented occasionally lost the plot. The mission as portrayed in the movie wasn't so clear. Arthur is saved from the destruction of the planet, only to be thrust into this mission of Zaphod's for no apparent reason. All the while he's pining over Trillian, and while she's receptive, it's more of a stalker, nagging subplot than anything significant. The weird bit about the mission for "the gun" was just plain dumb. It's as though the studio or screenwriters that took over after Douglas died couldn't make reason out of the book, so they threw the quest for the weapon in there.
Sadly, I couldn't recall enough of the book to make a fair comparison, so I picked up the new five-part trilogy (plus short story) to re-read. There is a sixth book, but it wasn't incorporated into the "ultimate guide" yet.