I found a copy today and played around 4 hours with the lady tonight.
Absolutely amazing! The pacing and the controls are a bit more intense compared to It Takes Two, so my girlfriend had to adapt a bit (she does not play games) but in the end we never had much issues. I recommend for you to play as the brown haired girl if you play with a casual gamer, as she seems to have more difficult phases.
And damn, the set pieces, the bosses, the side worlds, the high level of polish.. this game is bloody brilliant and feels like a step above It Takes Two!
Can't wait to continue tomorrow.