I find the UI look of the Cycles branch, despite just a few changes, to be vastly better looking and less confusing than that of the “normal” release. The panel headers are absolutely superior, as one can actually start to distinguish panels effortlessly. The absense of all those widgets like those for forking/joining spaces are what I was waiting for, very good !
I would like to see the button for the space type to go away also, it just eats space for no reason. The right click menu can take care of that, just MHO.
The only thing missing are the plus buttons (but not their ugly looks and layouts) for the shelves. But then, I really dislike the shelves (sorry about that) as they also eat space in a dictated and uncomfortable way.
Anyway, whether inside in-view3d shelves or not, all the tools there should really be grouped inside tabs, not panels (the “Mesh Tools” panel is also too gigantic anyway and should be split) as it’s really uncomfortable to (un)fold panels back and forth and scroll up and down all the time. Modo has done it almost nice, almost because orienting text (for the tool groups) vertically is not as nice as icons that can be much smaller and not become unreadable due to certain space layouts. I’d like blender to utilize the tab system for grouping tools.
I hope it doesn’t stop there and keeps improving. Would be real nice if as much of the UI properties as possible were themeable.