To turn off the Emulated LCD colors in BGB that look washed out:
-> Right click on the emulator screen -> Options -> Graphics
-> GBC LCD Colors -> Uncheck "Enable"
The art and overall feel look really good. It all fits well and has a great tone. Music sounds good too.
My only suggestion at the moment is a personal preference- having the Coria's movement freeze while slashing on the ground makes the movement feel a little stiff instead of smooth, it would be nice if movement was still possible when doing that (as it is when slashing in the air). I also understand it's usually a deliberate design choice with reasons for it. :)
(for the programmer) By the way, BGB is reporting an Uninitialized WRAM access exception on startup. You can turn the exceptions on in the Exceptions Tab of the Options panel. It's a good way to catch potential bugs.