Just got out of seeing it with my family. The question that we kept speculating on was the obvious one. Who is Rey and what is her lineage? Our theories ranged from the "So obvious that it can't possibly be right" that she's a Skywalker, to the "Less obvious but workable" that she's a Kenobi or a Jinn, to the "So completely batshit insane that it can't possibly be anything other than 100% correct."
Namely, that Rey is a clone of Shmi Skywalker made by the last remnants of the Sith. In a desperate attempt to revive Vader, they've cloned his mother, the person who created him, and placed her in the exact same situation (sold in to slavery and abandoned alone on a desert planet) in hopes that she will magically become pregnant by the Force again and they won't fuck up this time. When it was mentioned that she dreamed of the ocean and an island, that was referring to the cloner facility on Kamino.
So, you know, the basic stuff.