I'm firmly with those who do _not_ want to see a 'modern', minimalist UI. The point of going with a classic UI isn't nostalgia (I still play the IE games because they are better games, not because of nostalgia), but because of atmosphere and aesthetics, and not looking like every other generic game. A classic UI is the way to go to achieve a more mature feel, and really add to the tone of the game. A minimalist interface would almost certainly make the game feel much more 'gamist' - where hack 'n slash is more important than story or atmosphere. The only concession to minimalism I would like to see is a reduction from the BG 3 bar system - a single bottom bar (more like Placescape, which is what you seem to be doing) or on two sides would probably be better. I have no problem with people being able to customize things to be more minimal, but the default should encourage the aesthetic as much as possible.
That said, I do agree with some of the specific criticisms that need to be made. Obviously the IWD2 icons above the portraits need to be updated, as I assume you plan to do (it's a bit unfortunate you chose to use that game's graphics for your mock up, since it had by far the worst all around aesthetic of the IE games - in terms of icon design and portrait style, BGII and I would respectively be the best models). And I would prefer the portraits to be larger, preferably the full height of the bar (they're an important part of the games aesthetic, and hopefully also one of the main ways of conveying information about character status - incidentally, I prefer the old system of having damage be blood colour on the portraits to a rather ugly red health meter). This does make it harder to know where to put abilities though. Moving the dialogue box left is also a good suggestion.
