Just upgraded to build 286 of the Designer yesterday and the UI is very elegant but I could use a little more contrast. In particular the sliders for the toolbox, inspector and config are hard to see and it is difficult to tell when I have selected text.
Noted! We are constantly tweaking the design, it will evolve quite a bit before we go into release. The clean theme was our first attempt at creating a solid base for moving forward, you will have quite a few surprises in the upcoming releases.
I actually thought the toolbar buttons were disabled at first, so didn't try to click on them. I also can't see a way to change the font size/name for the code editor, nor does there seem to be a way to get rid of that nasty white line at 80 chars (?) down the screen, and the white toolbar between the canvas area and the project inspectors is a bit of a waste of screen real-estate, for just two buttons. There's also a grey status bar along the bottom of the screen which seems to serve no purpose? and the toolbar itself needs an option for buttons without text or to place text beside buttons (it's also a bit chunky for just six buttons).
But I am seeing definite improvements in this release, so I don't want to sound completely negative :-)