Yes, it's not the book. Yes, it's not the best version of the movie, and they drop as many threads as they wrap up. And they don't say the question(*). That's unforgivable.
However, people who deified Douglas Adams have forgotten one thing: he was a hack. He could only write really well when he was broke enough to have no choice. The fourth book of the H2G2 trilogy wasn't great, and the so-called 5th book of the trilogy (*gag* Mostly Harmless) isn't fit to line my cockatiel's bird cage (Sunshine might actually read the pages...). Terry Jones had to write "Douglas Adams' Starship Titanic". Adams isn't Shakespeare.
If you keep that in mind, the movie really fits the tradition. It stands on its own, but helps to know the backstory. I wish they had carried through with the Question, but they simply didn't have enough time. But I really cared about the silly everyman who was losing his home, his planet, yet wasn't losing himself. I may want to be Kirk, Spock, or Obi-Wan, but down in my heart, I know I'd probably be Arthur Dent, and if you think about it, so do you.
I'd rather watch H2G2 a hundred times than watch Star Wars Episodes 1 through 3 one more time.
(*) What is six multiplied by nine? Forty-two.
Yes, it works.