Exactly because it was not predictable from my past reading of the books or the watching of the BBC series. The BBC series has a better pace and better delivery of humour, though I disliked some of the actors.

Speaking of spoilers, the only thing that came as a surprise to me was that Zaphod was the one who signed the proclamation for the hyperspace bypass. Don't remember that this was in the books or the series. Wonder though whether Adams was engaging in a bit of Lucasian revisionism that tries to ties things together in a knot. As for the romance, we have to consider that the later books in the series were a tad more romantically inclined. Probably Adams also doing a spin on his earlier works based on his later outlook.

I can't say that I really got much pleasure from viewing the movie. Made me cringe in places - especially based on the pacing that you mentioned, and bored in many others. My 14 and 9 yo's did enjoy it though. The 14 yo has already read the series and my 9 yo started reading the first book after we got home. So it wasn't a total loss after all.