The bad stuff:
I like some minimalistic details, but there is just so much unneccessary clutter. Combo voices are annoyingly off-sound, 'copyright' stuff on the side lines of o!m, those faces for mods... And the sounds that play when you click on the menu omg. They annoy me. Previews have a word "Preview" on it, which is logical but oh so unneccessary, because it covers what little stuff you could see there. The lower part from back button to F3 ends abruptly and make it look like there is supposed to be something else after that button but it was cut off. Miss sounds, ugh. Pause menu isn't transparent, which isn't a BIG problem, but it's annoying tbh. Score font isn't cool and compared to everything else in this skin looks bland. Taiko face is horrible. Osu mode's sliders' circles have very revulsive and diverting graphics. And the color palette just isn't to my liking.
Oh and spin circles are horrible and I want to shiv that monkeytrafficer who made the moving circle almost unnoticable xD
The good stuff:
Really great SE on clicks and map changes, great animations, combo scores look simply gorgeous and don't clutter the screen, CtB's character is weird, but I like her, plus the pastels and outlines are nice additions, mod pics are great (but I'd love them to be a bit bigger, I know it's design stuff but I just can't understand what they mean unless I read the text), nice design on sliders and buttons, combo connectors are easy to see, amazing palette for osu mania and just the style of it is amazing
Conclusion: If you focus ONLY on the game, there is little to no clutter and everything is great. But you can't just cut off UI, and it's very, very weird and diverting, especially in standard mode.
Color palette: 6.5/10
Design: 8.5/10
Usability: 5/10