I hope the overall genuine funny/ dark/ sad tones they seem to be able to pull off in their games will come through. There's a gravity in the writing that Obsidian's writers hit that endlessly draws me to their titles.
Some of my favorite writing in general is using seemingly mundane tropes and genres, feeding you more of the same, and then cork screwing it on it's head. Of course I don't know any more about AP than any one else waiting to play (probably I know less actually) but seeing how Obsidian's done things in the past I'd put my $$$ on there's going to be some big Oh **it! cards being played through the game.
Well, those are the main things I'm interested in. Writing, and atmosphere/tone.
Based on that infamous "choices" video, I think that the choices you make in AP will have genuine consequences on the story, so I'm not so worried about that.
But Obsidian has a track record of excellent writing. Quite frankly, it's inexplicable to me that David Gaider got a novel published before Chris Avellone (where's the novel, Chris ? You know you want to do it... )
I certainly agree that there is a "gravity" to Obsidian's writing that draws you in. The precarious balance required to tastefully mix humor among the bleak settings found in Torment and Fallout also hit the right spots for me as a reader.
Atmosphere is also something that was very well done in those old games, and MoTB also had great ambience and mood. Even Icewind Dale, especially places like the haunted Severed Hand, painted a very rich, palpable sense of atmosphere in the player's mind.
So if writing, and atmosphere are well served in Alpha Protocol, then that will suffice for my nostalgia.