I don't know about the Finn guy, but I'd say explanation for Rey is that she is obviously "The Chosen One" and not Luke. I'm sure the writers have the next movies plot lines pretty much hashed out, and they obviously want us curious why she is even more powerful than Annaken or Luke was in terms of raw untrained power. She will be the one who balances the Force.
I liked the actress who played Rey, and thought she did well. The problem is, at least to me, the character Rey came off as far too Mary Sue-ish for my tastes. In the beginning, I thought this might end up being a problem with Finn, but even Finn had his failures and weaknesses (though I do think his effectiveness with a saber was pushing it a bit too far). Rey, on the other hand, was just great at literally everything, all the time.
Climb a sheer face with ease? Check. Fine, I can give her this one since she has a established background as a scavenger.
Effectively start using a blaster with ease even though it's rather clearly implied she isn't experienced with one? Check. Even Luke wasn't exactly great with a blaster starting out, despite the fact that his previous experience shooting womp rats is referenced.
Automatically and immediately learn to defend against and employ Force powers, including Mind Trick and Telekinesis, even in contention against a much more experienced and trained user? Check. Unless I'm forgetting something, Luke wasn't shown using Mind Trick until RotJ, after having trained with the likes of both Obi-wan and Yoda. And his Telekinetic power was still not mastered by ESB. Rey, OTOH, defends against Kylo's interrogation almost automatically, and then after a mere couple of tries, completely Mind Tricks the Stormtrooper guarding her, and then proceeds to overpower Kylo's telekinesis... Zero training, zero experience. From knowing nothing to becoming magically proficient in Jedi abilities inside of a 24-hour period. Mind you, it is established that Kylo has had training under both Luke and Snoke, so much training, in fact, that he had been able to successfully betray Luke, and went on to become the leader of the Knights of Ren, which I assume is a position of some note.
Great pilot? Even using ships she has no experience with? Check. Even Anakin as a boy was really just winging it when he gets into his first ship, and he also had the help of R2 as well. Plus he also had a bit of podracer experience, which while not the exact same is certainly related. That being said, I'm prepared to give her a pass here, as it has been established that Force sensitivity tends to lend itself to piloting, as we've seen with both Anakin and Luke, among others.
Great techy? Check. She fixes the Falcon in a way that even surprised Han right after flying it for the first time.
Great at melee combat? Check. In one of her first scenes, we see her successfully fight off an entire group of assailants with ease using her polearm. But that isn't enough, no she's also apparently great at using a lightsaber as well, as she successfully defeats Kylo (again, established training), despite the fact that canonically, lightsabers are unique weapons from traditional melee weapons due to the physics of their mechanics--you don't just pick one up and begin to wield it competently, especially against another who has had dedicated training. And yes, Kylo had been battling Finn beforehand, and did sustain damage from both Finn (but honestly, Finn should have totally failed at using the saber) and Chewie, but still... the proficiency with which Rey was using the saber was just a bit much.
Force sensitivity can contribute to some of these things--improved reflexes, perception, and the like... but it can't explain how great she was in all of these cases, using all of these different skillsets.
I think it was heavily implied that she is a Skywalker (and even probably Luke's daughter), but even if we, for the sake of argument, assume this is correct, and then go on to assume that maybe she had a bit of training as a child that she simply doesn't remember, that doesn't account for all of this either.
And while I don't expect Kylo was the greatest darkside practitioner, he clearly had plenty of competency and training. So, it isn't simply a case of Kylo being a total noob, either.
So, in the end, she just came off as very Mary Sue to me. Too good at too much.
Hide and watch.
