Yes. Highly controversal discussions over there. This is what happens when you follow a trend without to understand the underlying problem and solution. Monochromic icons works where they are super fat and just a few ones. A mobile phone for example. But they will not work in a UI with hundrets of icons.
It always baffles me how they manage not to manage it. It’s like they are simply not able to understand the problems when it comes to graphical UI. In this case the purpose of icons, how the human eye distinguish them, and why monochromic icons in this size is a very bad idea for most areas in the UI. They all look too similar then. And that’s what quite a few users already expressed. They have a hard time now with the new small icons. I have by the way already the same problem with the big icons in the tool shelf. A bit too similar in color and shape. The eye does not find an anchor here. But here they have at least a big size which makes it easier to distinguish.
I will use the old icons when merging and where available. They are ways not perfect, and are the opposite of the monochromic icons. A bit too coloured here and there. But they are much better to work with. And then let’s have a look how to continue. I have read that there is a patch at the way to allow user defined icons. But this is Blender, and so chances are big that this patch will never make it into trunk.