My GF and I played through the first few hours together in DUO mode... she controls Jodie (Easy mode), while I control Aiden (Normal mode).
I must start by saying that the graphics are absolutely fucking phenomenal and completely floor me as we play... This is damn impressive on PS3. And given that most environments are actually not completely tiny and you can look around and such, it makes you realize that the graphics are not only this good due to the style of game... I think this engine may be capable of a more hardcore game and still look the same. My biggest worry was that the graphics would be amazing but it would be screen-tearing the whole way through. I was delighted to discover that it has V-sync and actually runs at a fairly smooth framerate... it feels easily above 30... maybe 45?
As for the Story, I have mixed feelings about it. My GF loves the time jumping back and forth, while I agree that it is necessary... but I feel it is necessary because if you played through these exact same sequences linearly, I bet that the gaps in between them would be incredibly awkward and even more confusing. How you get from E->F is not as important when you experiences it as E->A->G->D->B->F... if it went from just E->F, I'd be asking "Wtf? How did I get here from where I last was? How much time has passed?" The non-linear presentation kind of eliminates this problem. I tell myself "Oh ok, this happens some time between D and G... cool cool."
But with the non-linear nature of it, the impact of pretty critical moments are definitely getting lost... I just did a fairly action heavy and down right frightening sequence in the story... and it felt out of place.
Also... I must say... as amazing as the graphics are, the moments when frightening "things" are shown are handled pretty terribly, especially at first. It's like I'm suddenly seeing effects out of a low budget game or something...
I chose to play Aiden while my GF plays Jodie because I was under the impression that I would get the most complex gameplay. In a way I do since i need to do a lot of flying around, locking on to enemies, and using a few different abilities. But she gets all the complex QTE sequences and "button twister" sequences. She's getting the hang of them though. But as she plays, I see how there really is ZERO consequence to screwing up any of the QTE moments. If you are being chased, you won't get caught. If you are fighting, you won't get hurt or killed... etc. The training sequence had the most consequence, and while I don't need this to "feel like a game", those sequences actually did and it felt very satisfying. But I guess Jodie can't die if you already saw her in the story later in her life... so that's another thing held back by the non-linear nature of the game. I just realized that now... damn.
Overall we are very much enjoying playing the game together. I'd strongly suggest playing in DUO mode if possible... it is a great GF/BF experience, IMO. She's amazingly not getting frustrated with it, and I think that's because she won't need to repeat something over and over if she fails... and she's gripped by the story, perhaps more than myself. I just enjoy playing something with her like this.
And at the end of the day, we had to downright force ourselves to turn off the game last night to avoid going to bed too late... that speaks volumes as well.