Hey, if Adams wanted Hugh Grant, who am I to complain? Wait, Lucas wanted Greedo to shoot first. Who are creators to determine what they create?
I wonder if they'll get Diaz to fake an English accent? Shouldn't be too hard... look at Xena. Her accent was utterly fake, Lawless normally talks just like a normal Kiwi. I didn't hear anyone complaining.
But Jim Carrey as Zaphod? I'm actually looking forward to that. The man's just crazy enough to make it work. The guy they had on the original TV series was OK, but he didn't show the glimmers of brilliance that occasionally permeate Zaphod's skulls. Carrey could do that perfectly, and hold a conversation with himself to boot.
And the effects might be a little better than the miniseries... Marvin can only get better. (I'll be pedantic here and state that 'extremely futuristic' is very definitely something Adams would have wanted; no grimepunk spaceships, no big girders holding things together - it's in Life that the Trial of Krikkit is held billions of years ago in a then-hypermodern concrete and steel room. The implication is very strong that what we think of as cool and modern today is not cool and modern in the galaxy.)