He copied the anchored menu bar, moved the window controls to the left, copied exposé, copied some elements of the OSX panel, tried to improve typography, etc. Some of these were actually good developments (the Ubuntu branded font set is nice) but most of the time it just feels like a cobbled together interface.
It also seems he is trying to copy some other elements of Apple. He is eschewing customization (ostensibly) for uniformity and simplicity. And he has made Canonical's designers the top decision makers. Programmers implement. Community gets what they're fed. Usability is their ultimate trump card (as we see in this case).
This doesn't appear to be working well, though. Apple hired world class designers and payed them tons and gave them a massive amount of power. And they had Steve Jobs who would say "this sucks" when no one else would. Canonical (probably?) has pretty good designers given near-absolute power. I'm thinking there's quite a difference between "world-class" and "pretty good". Not to mention that Shuttleworth, an amazing man in his own right, is no Steve Jobs. He probably doesn't say "this sucks" enough and maybe even doesn't know what actually does suck when it comes to design and usability.
Anyways... I wish Shuttleworth well but I'm not very optimistic about Canonical's future. And I think they'd do better if he brought his own personality, creativity, and intensity to the project instead of chasing Jobs' shadow. Or maybe he should find a new leader to take his place.