I have to disagree with this, at least to some extent. The 1973-74 films The Three Musketeers and The Four Musketeers (really one movie, split into two parts) is very close to the original material. I was prompted to read the book after watching the first film, which had a lot of humor laced in with the swashbuckling. I assumed that was just part of the film, but was surprised that much of that humor was in Dumas' novel. The second film came out after I finished the book, and it confirmed that the Richard Lester films closely followed the book's narrative, plot and tone. Adding to the pleasure of watching those films is the fact that there were no CGI in the epic fight scenes. They are all real people doing real things. In my view, these films are just as satisfying as the book -- which, as you say, is terrific fun.