Edit: Post cocked up apologies.
I thought Kylo Ren being a petulant child was exactly what was required. He's tormented between the light side and good, he reminds me of Anakin from the poor prequels; wanting to be powerful and mastering the force, but not having the discipline to be able to master it. He's almost showing off with his use of the force to intimidate, but actually is very insecure, thus his control over the force is poor. I also think he hasn't encountered another force sensitive/enabled person - which further throws him off his stride. I think he makes himself therefore a perfect candidate for corruption which we shall see.
I also wonder whether or not Snoke is Darth Plagueis since the EU is going to be mainly ignored (from what I hear). Although Darth Sidius supposedly killed him in his sleep, would Darth Plagueis actually let that happen? Either way it'll be interesting to see how they take that story further. I don't have an opinion on either argument about this.
I think the film could have benefited from being a little longer, to give a better sense of time elapsing for Rey to develop her affinity with the force, and the time taken for the First Order to discover them at Maz Kanata's place, it felt a little rushed in places. Also a lot of people didn't realise or take note that Maz is a pirate/smuggler that has been alive for over 1000 years, so her getting her hands on Luke's lightsaber is not inconceivable, but also it could have been done on purpose (planted), owing to Luke having a vision about Rey's coming... who knows!
I guess Rey always "knew" - a bit like how they portrayed it in Episode 1 with young Anakin being a pod racer and having "Jedi like reflexes". She was pretty skilled with her staff too, and a bit of a scraper, Kylo was also badly injured so I guess that's probably why / how she bettered him. However I felt that they could have made that clearer.
With regards to Luke, there is clearly more to the story than we've been told given Luke’s lack of dialogue so I'm looking forward to seeing that story line develop.
Yes the typical weakness of a big planet destroying weapon was a bit
'been there done that', however, I thought it was great, "How do we blow it up? There's always a way to do that."
It was also interesting to see Solo accepting that the force is real, Jedi and Sith - which probably reinforces Rey's affinity.
I'm still curious to hear about Finn's history, where his family is from etc... is he force sensitive too?