Haven't seen the movie because crowds. But I did just finish the novelization. So while I can't really comment on the visuals or directing, I can talking about the storyline and spoilers.
SPOILERS -- though at this point, people should know to just stay out of this thread.
I thought both Finn and Rey became weaker characters as the story went on. Finn never had that air of being a supercharged badass, which I really liked. But after opening act had him and Rey forming a pretty solid partnership, he really lost almost all of his power. Dude was supposed to be an awesome marksman, but they totally take away his gun for the final act. Instead of him growing into the role of legit fighter, he was pretty much relegated to be emotional support for Rey and to be the damsel in distress. And he gets friend-zoned while in a coma. How sad is that?
His arc can totally be redeemed in the following movies by him either learning he's force-sensitive or figuring out how to be a worthwhile character despite having no force powers (like Jango and Bobo). I don't see why he can't become better with a lightsaber anyway. But I could also see him being completely marginalized in the next movies to make room for the Poe/Rey lovefest. I actually don't know what would be worse for Finn: For him to let himself be cucked by Poe or for him to be part of a stupid-ass love triangle.
Rey was best when she was a resourceful girl, kinda like a female Han Solo. Her being able to defend herself was cool, and as I said, she and Finn formed a solid partnership, which is something you rarely see between men and women in movies. The fact that they essentially took the qualities of Luke, Han and Leia and shuffled and combined them into two characters was very welcome for me, as it took away a lot of the fat that hung on the trio in the original trilogy.
Things started to fall apart as soon as she got the messiah treatment. After that, she pretty much got every cool point. The producers want to act like her arc is new or even not worn out, but it is. , pretty much every movie made about a female YA book has girls who are combat savants and who end up becoming way too powerful for any logical progression to justify. If we have to watch two more movies of her becoming the space version of Katniss, it might completely kill the series for me. I have no issue with her being a Jedi, but damn it if she is going to just be able to do everything on her own because the producers are determined to secure support from feminists.
Ren wasn't bad to me. What was wrong with his character is what's wrong with the whole series. It's never made sense that you only have two choices when using the force. Games like KOTOR tried to show that there was a lot of gray area. I don't get why it would be hard to just have Jedi powers while being able to think for yourself? And since when is having emotions NOT okay for the dark side? It seems like they would be the group that would allow themselves to act viscerally while the light side is all disciplined. Then you have the true id/superego dichotomy.
I think the final battle would have been stronger had Rey used the saber teamed up with Finn (who's using a blaster) to hold off Ren. Sort of like the final battle of Windwaker. Like Ren can't finished off Rey because he has to keep deflecting Finn's shots, but he can't force-push Finn away because Rey attacks anytime he tries. Then, you could have Ren go balls out and wound Finn before Rey strikes him. Would get you to the same situation while keeping everyone's integrity.