Here goes a quite detailed review:
Intro: 4.4 (a teaser to whats comin up)
Title and the plains: 4.8 - 5.0 (close to perfection)
Underground: 3.8 - 4.3 (Drops slightly in quality, but when compared to the plains, what music does'nt)
The castle: 4.2 - 4.5 (overall fine pieces that really suits the atmosphere and the slight increase in difficulty)
Water (last level): 4.1 - 4.8 (music is of quite uneven quality even within tunes ranging from just good to superb)
Game Over (when you die): 4.2 (far from as good as SOTB2 deathscene but still a fine piece)