I was trying to keep my big mouth shut, while reading this thread, but Raven, how is turn-based versus real-time not part of the game mechanics? Lumping that in with the interface seems equivilant to saying the big difference between FreeSpace and Baldur's Gate were some minor changes to the GUI. Sure, the interfaces are different. There's no lead indicator ahead of enemies in Baldur's Gate, and I haven't got a quick-slot on my FreeSpace HUD for casting Cure Serious Wounds, but that's quibbling over details, while missing the grander picture. In a less extreme example, consider the differences between Civilization and Command & Conquer. They're both strategy game series, but the gameplay is fundamentally different between the two, primarily because Civilization is turn-based, and C&C is real-time.
Anyway, I think that there's not enough information out there to tell how faithful Bethesda will be to Fallout's style of gameplay. They're certainly keeping with the art style of the old Fallout titles, which is promising. I put myself in the camp that says a true sequel should have gameplay that at least resembles its predecessors. If Fallout 3 is turned into a real-time, first-person affair, it will probably end up feeling more like a sequel to STALKER than Fallout.