I know it's just a WIP, but I have to wonder. Why do you show some of your debuffs like 3 times on the target? Having a castbar like that is a "neat" idea, however without a ToT it suddenly doesn't look neat anymore and to me it kinda brings the UI to the right side, making it look strangely aligned. That and do you have to know what spell you are casting? A man would think you know what spell you are casting. As for the cast time, in my experience it's something you really don't look at in a combat situation.
Also you use 1 row of actionbars, I guess this is cooldown related, but below that there is a CD meter. So I don't understand why you show the actionbar and the cooldown meter.
And as 1 final tip I would try to move the text on your UF's to the top, not above the UF, but still touching the UF for a pixel or 2-3. Now it's kinda in the small middle emptiness and it could again be me, but I feel like interferes with the possibility of immediately seeing your healthbar and power bar. That and, do you constantly have to see what your maximum health and mana is and a percentage?
All in all not a bad start, but in my opinion you could also just get careUI which is the basic idea anyway, just better.