Ys III has one of the most remarkable soundtracks to this day in my opinion, it also beats Book I&II which already set the bar high. It cannot match the introduction though, Ys I manages to deliver a certain mood, feeling and also initial hype through the three parts (background, title screen and kick-off intro) which few games have managed to do (its sequels failed at it too, but Book II does it better than Ys III).
The Ys III soundtrack also sounds way better than any other version of the same game, even the newer ones. The added violins of the PC/PSP version were a nice try, but it doesn't get close to beating the PCE arrangement.
I've shared the ridiculously poor American dub with a couple of friends and they both asked for the title of The Boy's Got Wings. I've also discovered this game in recent years, so no notalgia involved.
Other aspects of both of these games are good but not astounding. Gameplay is solid, story is basic, graphics are good but unimpressive, except for the intros. These were also made in an era when artwork was amazing in general, but again in Ys's case it was decent but not up there with the best. And yes, I belive that external artwork (box art, manual illustrations etc.) were important parts of the games themselves back then.