I rather like the first book but the other ones just weren’t very enjoyable. They had glimmers of greatness in some chapters but overall they never delivered like the first book did. Personal opinion however.
I am curious though, someone had told me… or perhaps i heard/read somewhere that Adams was never really keen on writing more after the first book, and wrote the sequels mostly out of obligation. Which seems likely to me considering how the story progresses, but i don’t know how true that actually was.