The notification slide is dark grey and slightly translucent rather than pure black (if you have a dark wallpaper - I don't know whether the light theme has changed). That's about it for visual changes. I think it's mostly under the hood stuff (e.g. activating their new image processor).
(I have sent Google feedback that it's less attractive, lower contrast and, since it looks like my HTC did 3 years ago, rather old-fashioned looking. Doubt they'll listen, but...).