Yes, the dock is really awful. In fact most design decisions in Mavericks are pretty bad.
White is such a hard background to work with -- you really need a balance of dark and light on a screen to be comfortable. Mavericks is really white, most of the time.
I think Apple is trying to copy Google and thinks simplicity in colour and design mean stability, ease and a robust, effective UI. Not sure I buy into that.
As I work with Mavericks and see that awful dock colour right off the bat, I feel like maybe the OS isn't loading graphics or BG images -- it feels like things are missing. So right away it doesn't draw you in, but makes you feel uneasy.
On an interesting note, if you go to the App Store, which is nicely designed, Apple uses lots of lines, shading and enclosing boxes. They needed to do more of that to make the UI work, in my humble opinion.
Anyhow, yes -- the dock colour *****! Some nice touches to the new OS but design, is not one of them.