I think everyone who uses Visual Studio can agree that Microsoft has packed an amazing amount of functionality into one tool. One thing that makes that possible is the ability to quickly get to all of the functionality easily not spending a lot of time sitting around RTFM. I am not sure about the direction that the monochromatic icons in the VS 2011 are going.
Here is a snippet from the VS2011 tool bar
Here is a snippet from the same tool bar in VS2010
I narrow down all of the little icons that I am looking at very quickly by color association. With that gone, I find I spend more time looking at the shape of each icon to understand what its function it.
I know that I am getting older, and as a result am fighting hard against the curmudgeon tendencies that go along with it, but it seems to me an important dimension is being removed to allow the quick association of icons based on color, in favor of style preferences.