Being a people pleaser, I agree with both Harry and OtinG.
I also wrote manuals (pre-internet) and PDFs
were great. I still remember how excited people were when we could DTP them ourselves and then have the PDF printed. Good times. No more printer's proofs back & forth. Oh, frabjous day(s)!
But where they're also
still good though is for writing specifications and procedures for distribution that
can't be altered (easily). There were even some documents that we produced that couldn't be
printed (or cut & pasted from). Using the Adobe tools, you can limit all sorts of things that the end user can do, and while this sounds a bit...OTT, it was really vital in our industry (because with Word docs etc unscrupulous people would change the documents and then there'd be even more lawyers time/money when things went wrong).