And I'm not the one saying this. Well, it's not exactly what is said, but I needed an eye-catching title ;-)

Finder X is the compromise between the Mac OS folks and the NeXT folks. Neither won, everybody lost.

Oh my god, the entire bastardized notion of switching from metal to aqua and hiding the sidebar when clicking on the toolbar chiclet in the upper right-hand corner.

Bonus: notice how if you click on the extreme right of the chiclet and try to switch back, you fail -- the window theme switch moved the chiclet slightly to the left and now you've got to follow it. Gag. Folks, this type of stuff makes Gnome look good.

Source: Jonathan Rentzsch, in this interview.