One of these books is not like the others...
Be forewarned: while this book is unmistakably a Hitchhiker's Guide book, it's also quite unique among the series. If you're in it only for the zany off-the-wall humor, well, you might not be disappointed because there is certainly plenty of that here, but Adams proves he can do so much more. Notably, the love story between Arthur and Fenchurch is quite moving, and as a result Arthur's character takes on whole new dimensions.
While I love Zaphod as much as the next guy, his absence here is actually a welcome reprieve, since he wouldn't fit in too well with this particular story. Unfortunately, however, it seems he's disappeared for good.
The ending is sort of, well, hmmm?, even though Marvin does make a last memorable appearance, but the rest of the book is good enough that one can't be too disappointed.
Martin Freeman's narration is quite appropriate and enjoyable--but I can't compare it to Adams' own, as I haven't heard that version yet, so take it for what it's worth.