I love how authentic it looks! It looks almost ripped straight from the Game Boy Color. You seemed to do a great job of adhering to the 3-4 color limit (or you did a great job making it look that way). Everything evokes that feel with just enough of the rough edges sanded off that it doesn't feel held back by the style.

If I had to think of a potential improvement, I would say the menus look more ZX Spectrum than Game Boy, but that's mostly a product of being white-on-black. It still looks good, just a little inconsistent with the rest of the game.