I like this mockup.
It is essential to be able to stop and analyse combat/conversation log to get precise info occasionally, but I don't need it most of the time and having it toggle able and on the side is ok.
Maybe an option to make it an extension of the main bar in the centre would be nice too, though.
Combat log runs too fast in RtwP game, when you hit multiple enemies with AoE it flush, or when you are interested mostly if you were succesful at damaging a boss, it is hard to spot his line when it scrolls constantly.
Tiny numbers and icons floating over the heads in addition to log, give less precise but much more direct and sufficient most of the time feedback, it also better visualises which exactly enemies get affected, by AoE for example, etc.
I guess that inventory/character/spellbook windows would pop up over the bar, leaving most of the gameplay area visible all the time, you could play combat with spellbook open for example.
Portraits are big, hate the tiny ones, it looks aesthetically pleasing overall and doesn't waste space. I would only change buttons for map/journal etc, for a bit larger ones with icons.