I'm happy that you are enjoying the game and drawing maps so far. I believe on GameFAQs that someone mapped out the devine area, but mapping yourself is quite fun (I had my little brother map out Keith Courage for me once so I could beat it
).
I agree that the enviorment graphic detail is a bit better in Book II and I think I can safely say the music is a bit better too. The awesome thing is that since you're only at the devine mines, I can honestly say that the graphics and especially music get better the farther you go along. You know this seems to be a symptom for all Ys games.
Anyways, enjoy the game. It's one of my all time favorites (easily my favorite RPG of any kind). The end of the game is incredible.