A few things that I'm sure have been covered, but sorry, I'm not reading 14 pages to find out (saw it last night):
1) Loved Rey. I think she's definitely Luke's daughter for a few reasons: There's the obvious connection with the lightsaber "calling to her" and the vision quest of greatest hits of the Skywalker line, but on top of that the movie prominently features her having three classic Skywalker traits: She's naturally gifted with the Force (and even more so once she "believes" ie. closes her eyes at the end, which Luke doesn't get until Empire), she's a naturally incredible pilot (after the Jakku chase she says something like "I don't even know how I did that!"), and she's gifted with repairing things (Anakin builds 3PO, Luke is fixing stuff for the farm).
I think after Ren fell to the dark side under Luke's tutelage (and with Leia possibly blaming Luke explicitly -- she says something like "if only I'd kept him (Ren) with me" to Han), Luke decided that Skywalkers are too dangerous to be trained. So, he goes in to exile and has to make the terrible decision to abandon his daughter on Jakku where he hopes no one will ever find her.
2) I thought Ren was an excellent bad guy, and as I expected going in, he's a conflicted bad guy. He's drawn to the power that the dark side represents, but he's afraid of not having the strength to be "fully evil." I also don't agree with people who see him as weak. We actually see him do some pretty powerful things with the Force, like stopping that blaster shot in mid air (I don't think we've ever seen a force user do that before), extensive mind reading, and effectively force paralysis. But those powers also reinforce the "conflicted bad guy" idea, because he does all of those powerful things with the force while he is focused and calm. Traditionally, calm and focus has been the realm of the light, with anger and chaos the realm of the dark. I think we can clearly see that Ren is a more powerful light side user than he is dark.
3) I'm unclear if Finn or Poe are going to turn out force sensitive. Both exhibit some of the hints of it (incredible pilot, skilled in combat), but I don't really see there being that many "Jedi" among the main characters.
4) If I had to guess, I'm going with Snoke being Darth Plageius from the PT. If I remember right, we know that Plageius can 1) save people from death 2) create life and 3) create powerful illusions. Perhaps he convinced Siddious that he was dead, but has been pulling strings in the background since the beginning. We could also guess that he was behind the Anakin being born from the Force, which explains some of the motivation for why Snoke is so interested in finding Skywalker (the descendant of the being he supposedly created). Also, someone posted a youtube doubler of the Darth Plageious / Opera music from the PT and the Snoke theme from TFA, they're very very similar.