I have to say I'm really impressed with OneNote MX, despite not being sure what MX means.
Metro Experience? (What does that make the Mazda MX-5?)
The radial menu reminds me of the four-paned context menu that 3DSMax has (or used to have, the last time I used it was quite a few versions ago). Max used it because they had an insane amount of stuff tucked in the context menu, though.
OneNote MX is very impressive, but I have to ask why I'd use it on a desktop when I spend most of my time in the desktop mode, also have the desktop OneNote, and when I use that I can actually see the stuff I'm taking notes about (overlapping windows FTW). I'm sure MX is great on a tablet, but I see no use case for it on a desktop PC.