I wonder if Splash Hill was the first zone art to be completed, and they didn't really "get" the look of the game down until designing later zones like Lost Labyrinth and Mad Gear?
I prefer the watercolor-like super detailed environments like LLZ over SHZ and CSZ.
In episode 2 I'd love to see a more realistic setting, like a dense forest, for the first act as well as an ice zone (always lovely to look at), a mechanical tropical hybrid and an environment not seen before in a 2D Sonic game.