I barely noticed the medusas in rondo of blood to be honest. There weren't that many sections with them in it (I can only remember 2 - 3), and even then they are not of the cheap degree that is more present in Castlevania 3 (I could also say CV 1, but other things gave me more hassle then the medusa heads).
Once or twice I can get caught off guard and they hit me down a pit, but mostly I have no trouble with them at all. Certainly not enough to invoke any form of frustration or rage. Only CV 1 - the first time around, sorta - and 3 have done that to me, and the frustration came from everything as a whole, and not focused on the Medusa heads. Maybe it's because I've already heard of their horrors that it didn't effect me when I played the game.
Although, if you're playing the snes port "dracula X", then that might be a different story altogether. Now that game I heard the cheapness is somewhat more present, especially the final boss.
Edit: Just to be clear, the snes game "dracula X" is technically rondo of blood, but different stage layouts,less maidens to save, and a lot more cheapness.