Yasunori Mitsuda has done an awful lot of very good music. Just look at Chrono Trigger and the original Shadow Hearts game. There really is a lot of quality music in this series, though I do prefer the original game in spite of it's not as great soundtrack. I'd actually forgotten how good that battle music was until I just listened to it on YouTube. It's really quite distinctive compared to the music of other RPGs that I've played.

As for whether or not it's dark or not, it really depends on the locations. The dungeons are really quite dark, particularly in the original. I feel that the sequel was somewhat weak by having many of its dungeons with the same music (think of the Rhondda, for instance), but still had some pretty strong entries. The wealth of its real-life locations was something I really liked about the games (I've never played the third), and it really appeals to a history nerd such as myself.

I realise this thread is quite old, but this forum is hardly the most active in the world and it was still on the first page.