I personally thought the way the games felt (atmosphere included) has changed SEVERAL times throughout the series.
Castlevania, Castlevania II, and Castlevania III all had similar atmosphere.
But I felt The Adventure and Belmont's Revenge were different, and kinda felt like typical GameBoy games.
Bloodlines, Rondo of Blood, Dracula X and The Adventure ReBirth all felt really poppy to me.
Super Castlevania IV, Castlevania 64, and Legacy of Darkness all had REALLY dark tones to them.
All Metroidvanias except Circle of the Moon felt the same to me.
Circle and Lords of Shadow have their own little feel to them.
Just my thoughts.