The best new character was the pilot and he is hardly in it all. Rey was good but way to emotionally distant and competent to really play the role they are trying to use her for. The protagonist in the hero's journey is supposed to start off weak and confused the build up to being the hero. She was a bad ass rom the start. That is why using Hans Solo as the mentor didn't really work, she never needed him and he didn't teach her anything. The mentor is supposed to mentor before you kill them off.
Finn was just OK and didn't really seem to have much of role to play beyond sidekick for Rey. Once again Hollywood has sacrificed story for politics and much like in Fury Road they made the male character weaker than he should have been in order to make the female character stronger. The very heart of the feminist mindset and also the reason none of the new hero characters is a white male.
As far logic and plot go it is no worse than the first series. Remember Hans Solo walking out of hi space ship wearing nothing but a breathing mask or the over grown teddy bears taking out armored vehicles with trees?
In the end thought the reason I give a B+ and not an A is my daughter loved it but still went home wanting to be Lea or Ahsoka. Like most JJ Abrams movies I suspect this will make a lot money and gets lots of praise and then be forgotten. Look at his Star Trek movies. Everyone loved them but it was written for the fans boys and may no impact on the next generation. The millennials loved but they have they attention span of gnats.