I'm hoping for the best but understandably preparing for the worst given how badly they managed to screw up Thief 3 by taking the epic sized missions from Thief 2 (remember Life of the Party?) and reducing the scale of them by 80-90% on the PC because it wouldn't fit the XBox's memory...
It's already been confirmed the levels include loading zones like Deadly Shadows did, and the comparison I see most about level design from the people who played it, is Splinter Cell. In other words, it's not large free form exploration like Thief 1 and 2, but rather hub rooms with two or three fairly linear routes going into the next hub room.
Now forgive me for this unwieldy list, rope arrows only work on predetermined hot spots, you can only jump contextually, you remain hidden while leaning into light sources, the game has multiple places that force you to get caught and thrust into an
escape sequence, there's a "swoop" move that allows you to do a quick silent sprint through light sources while remaining invisible, there are quick time events (
they said they removed all the QTE's, they didn't) to keep players busy while the game loads within a level, arrows go into chase cam bullet time for some head shots, there are forced third person sequences and third person take down moves, the light gem only has 3 stages, you have to stand up to use doors, player upgrades including quieter movement, the screen flashes every time you move into light as part of the smoky shrouded HUD, and that's just whats off the top of my head.
To play devil's advocate, they added quite a few options in the menu for difficulty and HUD adjustments, and they half removed the leveling system, IE: ditched the XP, but just made all the player upgrades purchasable instead.