Completely – serving the dramatic purpose is the most essential component of a (cinematically) good sword fight. The Greatest Duel In Cinematic History (*) is actually, well… really bad rapier fencing at a technical level. But it’s still the Greatest Duel in Cinematic History, because it teaches about the characters, their motivations, and more, all while advancing the plot. And one of the best duels in Star Wars, in terms of providing emotional tension and characterization, is the brief and (to be blunt) technically pretty incompetent duel between Obi Wan Kenobi and Darth Vader.
For me, it’s choosing a style appropriate to the personality and/or philosophy of each character. While I can’t say it was a particularly good movie, I loved how Jet Li did this in The One, with different styles for each of his characters. It’s also one of the things I disliked about Star Wars Episode Two - a flashy flip-filled style is cool CGI but doesn’t really suit Yoda’s personality.
I once made a reel of my favorite movie sword fights. Watched all the way through. (Pre-YouTube, mind you). Boy was that dull. Without the dramatic context, sword fights aren’t nearly as engaging. I still watch movie clips, including sword fights and stunts and all sorts of things to study the technical details, but they really benefit from the build up and dram of the production, and vise versa.
“In the famous “snapping” sword fight between Danny Kaye and Basil Rathbone, Kaye’s sword movements were too fast for Rathbone, who was 63 at the time. The fight choreographer dressed up as Rathbone’s character and was filmed from behind for the fast sections. If you look, you can see that most of the fight consists of Rathbone from the back, then shots of the real Rathbone standing en garde.”
The ones in Empire Strikes Back seemed to be the most realistic—not ad-libbed as an afterthought like in the first movie or faked in post-production like in all the other films, but instead the actors actually holding big heavy electric swords and performing actual kendo techniques
Jill Bearup has kept me quite entertained with her YouTube sword fight reviews and analyses - her Princess Bride analysis in particular (on youtube at j0rkUbrPo3k, since my newly-born account appears incapable of posting links).