Stopped at the Pride of Frankenstein.

Tried this for its historical significance, but I didn't have very much fun. Simon moves incredibly stiffly and some areas require extremely precise timing and positioning to progress. That said, the level design is very tight and perfectly tuned to the player's abilities. The graphics are evocative and make excellent use of the limited NES capabilities. By far Castlevania's best feature is the music, which ranges from creepy to intense without a single bad track.