Agreed. I read them as slowly as I could manage over the course of about five years. Even 21 was a great read. I was blown away that I was still maintaining the same enjoyment 15, 16 books in. I just assumed the quality would have had to deteriorate. Although O'Brian does get a lot of reuse out of Stephen's joke about the dog watch being cur-tailed.
I wish I still had eight and a half more to go!