One of the features I was most looking forward to with the release of Mavericks was the promise that I could have access to the menu bar and Dock on every monitor. It might seem like a minor tweak, but it's always annoyed me that I had to pick one of my screens to be "in charge" of things, when I'd prefer to be able to launch and manage my applications from either screen, depending on which one I'm working with at the time. The promised top menu bar multiplication has arrived as described, but unfortunately the "Dock for every screen" bullet point comes with a big, fat asterisk.
You see, I'm one of those weird people who doesn't let his Dock sit at the bottom of the screen -- I like my Dock to sit vertically on the side. The way the multi-screen Dock works in Mavericks requires you to place your mouse cursor along the bottom of the screen on whichever monitor you'd like the Dock to magically appear, and this simply doesn't work if you have your Dock located anywhere but at the very bottom of the display.
I know, I know, I'm a small minority, but the vertical Dock configuration is just what has worked best for me over the years, and it seems Apple hasn't come up with a solution that lets me, for example, have my Dock appear on both the far left and far right sides of my multiple-display setup. It seems like this type of change wouldn't be very hard to implement, but the moment it's just not an option. Bummer.