Douglas Adams - of The Hitchhikers Guide to the Galaxy fame - would have been 72 today, if he had not died in 2001.
Is he overrated? Yes - in the sense that he is regarded by many people as one of the great comic writers.
My evaluation is that Adams was only great in Hitchhikers Guide, all his other work being second-rate (or worse) - therefore he is essentially a one-hit-wonder, rather than "great".
Furthermore; it is only the first and second BBC radio series of Hitchhiker's Guide broadcast 1978-80) that were truly, unsurpassably, great - and all other versions and variations of HHGG are significantly worse.
Yet, Adams cannot take all the credit for the greatness of the radio HHGG.
It is instead a masterly collaboration; in which actor Peter Jones (as The Book) is vital; and so are the BBC Radiophonic Workshop; and - in general - the producers and directors responsible for creating the "soundscape" which was marvelous and unlike anything else.
Of course Adams's radio scripts are absolutely superb. I tuned into Episode Five of Series One, Sunday 5th April 1978, shortly after the programme had started. And, knowing nothing whatsoever about what I was listening to - I was immediately stunned by the sheer brilliance and originality, and captivated by the world Adams had created.
So I do not under-rate Douglas Adams - far from it!
But The LP recording (which I bought in 1979) was somewhat less good than the radio version; the novelizations (beginning from 1979) were nothing like as good as the radio; the 1981 BBC TV show was worse than any of the above... and so forth.
After the arc of the radio series one and two had finished in 1980, Adams's work described a progressively downward trajectory in quality. The later books were almost embarrassingly thin on ideas - it felt like the authors was squeezing harder and harder, to extract ever-fewer drops of inspiration out of ever-staler old ideas.
We ought to judge artists by their best work. As such, Adams best work was his earliest radio work, and he maintained that level for two years, that is six hours of radio.
Having experienced his best work before reading the novelizations; my evaluation of Adams as a writer of books was that he was always less than first-rate.
Therefore, insofar as Douglas Adams's books are regarded as first-rate - he is indeed overrated.