* The new look in VS 2012, without resize borders and without a distinct title bar make the product harder to use. The border and title bar are the only way to tell which window is active. I'm constantly unable to tell if Visual Studio is currently the active window, especially on a multi-monitor system. Trying to resize the window by gripping the edge is an exercise in frustration, since you actually have to grab _next to_ the window. There's no visual affordance to click and drag.
* The code editing windows no longer honor High Contrast Mode, as they did in VS2010. Not only does this result in a tremendous amount of glare for people with certain types of visual problems, but it is also impossible to read parts of the code, because the default for things like namespaces becomes white-on-white (or something very close to it).
(Fortunately, High Contrast Mode as least restores the title bar cues as to which window is the active window.)