the 3.93 marks this as least appreciated Hitchhiker's book, but overall, after a fairly careful re-read, I think it's fair to say the overall quality of the works isn't really changing that much from work to work, and the idea that there's a sort of meta-novel at work-- a UK novel about early parenthood-- might be grounds for calling the entire series a 4.4 and leaving it at that.
how would I rate the series if decimalization of ratings was permitted?
something like that. in other words, entries 1 and 2 were clearly the franchise; the fourth was a slightly weaker entry, but overall this is pretty philosophical, (and possibly meta) craftsmanship. half a million ratings on Hitchhiker's Guide to the Galaxy can't be wrong.
with the 'trilogy' (ha, can't resist the same joke everyone else is bandying about); with the trilogy drawing to a close and Douglas Adams--sadly-- departed, I suppose we can add the retroactive halo effect to deceased writers and call him a triumph of comic writing of the 1980s+ period. the tongue-wagging planet symbol will remain for decades to come as a victory for marketing--and will undoubtedly be relaunched in a decade or two much as Robert Ludlum and even Trevanian were relaunched-- but it's clear this meditation on parenting and young adulthood has accomplished something of note, even if it's not quite the liquid perfection of Hitchhiker's Guide and Restaurant @End of Universe. absurdist humor; always a scene in every work that redeems weaker passages; snide commentary on modern life disguised behind chatter about "the galaxy."
influenced a generation of absurdist sci fi; Red Dwarf etc.