Finn's ability to wield a lightsabre... I think we saw different movies. In the one I watched, he turns it on twice, waves it about wildly hitting people and then gets comprehensively flattened both times.
I thought he actually held up pretty well against Kylo Ren. Okay, Ren soundly beat him, (which was to be expected) but he held his own longer than I'd have expected.
I didn't really find that unbelievable though, when you consider that Stormtrooper with the baton thing. The New Order are aware that Jedi were instrumental in defeating their predecessor, so during their rise during the new Republic era (if you can call it an 'era') they make sure they give certain trooper's training in hand to hand combat with those special weapons, possibly even tech they dug up from the Prequel time period. (Considering those droids with those electrostaff weapons.)
Jedi might be a minority now, (well, basically just Luke after the destruction of his academy) but they don't want to take any chances, and I'd imagine those gizmos are pretty handy against other non-ranged weapons. Staves and axe type things seem to be in use within the Star Wars universe, as are blades of different kinds.I guess Finn had a bit of that training too.
Anyhow: Rogue One and The Force Awakens. I like them both. I feel the latter was constructed worse, being an almost beat-for-beat retelling of Star Wars (okay, Finn the defecting stormtrooper was a rather different element) and relying on fate/coincidence a bit too much ("Lets escape on that saucer shaped ship. Oh look at who just happens to be parked up in orbit...")but it was fun and had a good heart.
Rogue One however managed to pull off a much more original story, even despite being set between other films. It was bleak, sure, but it also had heart. The better of the two films, I think, from a structure/story point of view, but The Force Awakens, was FUN (apologies for repeating myself)!
I'm very much looking forward to Episode VIII. I'm particularly curios about Luke's line, right at the end of the trailer... (I won't spoil it for those who intentionally avoided the trailer.)