I also like the UI
Godrays, yeah, fells a bit weird that they overlap with the "ceiling"(?) Of the underwater cave. I was under the impression this was a section of a level and that the ceiling might be gameplay relevant, but since it is a menu screen, them maybe you could drop the ceiling? Let the god rays come indistinctly from above, and that ends the layer fight between the ceiling and the rays.
As for pixel friendly water effects, why not have a fullscreen shader that horizontaly displaces a few horizontal lines of the screen by one pixel, and have try too vertically? Eh, hard to explain but o remember seeing something like that in snes games for pixel based water distortion.