A suggestion: Some kind of visual indicator of people who are nearby but offscreen, and another indicator of anything that's increasing your risk. Hopefully when the stealth system is tied more to NPCs seeing you- it would feel appropriate to be able to make a mad dash away from someone, but the sound of you running attracts people. Have you played Assassin's Creed? The NPC-based stealth in those games is really good, perhaps you could get some ideas from it.
Really like the physics system in the game, very nice. The hands-tied overlay makes me wish for an option to play with your hands tied, so you can't pick up any pictures until you manage to untie yourself.