I think it is really important to see the information about cast/attack timing and idle time in the game to understand the combat better (this is a great chart btw if still accurate : http://i.imgur.com/WR2BQ1N.jpg ) , and I am suprised that BillyCorgan's ideas have been buried without any real debate.
Here is a comparison with a mockup I made with ideas borrowed from previous posts (and yes I suck at ps)
1) Action info on character portraits, showing who is idle ( BB Rogue) , who is recovering from a spell (BB Wizard) , who is casting a spell (BB Priest) , who is recovering from an attack (the PC) and who is attacking (BB Fighter) , with timers for each action.
2) Enemy info panel in the UI with action information, rather than blocking the main screen.
3) An action - queue bar at the top for the selected character that shows recovery time etc. and the queued actions. Detailed version of what we see on top of the portraits.
2 and 3 are optional of course, but something like #1 (with the timing in numbers) is definetely required ingame, in order to follow who is doing what and when. You can see how the pop up UI with the TAB button confuses the main scene with clustering elements on top of each character, and makes it harder for players to manage combat.
Also an indicator of weapon speed in the item descriptions would be a great addition. I think the "true RtwP" element of the game is fantastic, especially compared to the semi-TB system of Infinity games, but the interface communicates this poorly and definetely needs better visuals before the game ships.