I think combat is possibly slightly too fast, and very difficult to follow. I'd very much like to see some improved VFX and animations (such as hit reactions, more obvious casting effects) as well as ease of use features like target indicators for enqueued actions (even the old IE games at least changed the targets selection circle if you had a pending spell/action).
The big issue I see is that the exterior maps are very difficult to differentiate with the characters, and that, combined with the overlays, close positioning, and unpolished VFX/SFX make combat just seem frenetic and very non-obvious. It's much better in the interior levels, but it still lacks a lot of weight and polish.
Also I think you should look at changing your VFX blending from being primarily additive to premultiplied alpha, where you can use the alpha channel to mark out regions which are non-additive (leave the RGB channels the same), which will help readability (it came up in a Blizzard talk at GDC13).