I actually thought I mentioned that in my post but apparently I forgot -- the lack of a proper Luke lightsaber battle is fucking criminal. Instead we get this weird cocktease with a damn slow-mo Matrix-dodge. I have nothing against slow-mo in movies whatsoever, but it's not something I ever wanted in Star Wars. Call me a purist, but I like that the series has (had) little idiosyncracies that became "how Star Wars movies are". Even the flashback ruffled my feathers, though I think I could have dealt with that if served more than feeling like a shoe-horned twist.
And here's the thing -- I actually would have been FINE with the lack of a Luke vs Someone lightsaber battle if they had actually approached Luke's character in a different/better way. For example I'm one of the people who (retrospectively) dislikes that Yoda ever used a lightsaber, as it seemed beneath his character. But given the plot we did actually get, a good Luke vs Kylo fight (even if it ended with Luke doing the Obi-Wan-Kenobi "strike me down" trick) would've been...well, something.
@Wilshire
Your point about only light side users being capable of Force ghosting is interesting and along with the Sith-culture stuff is really the kind of shit I was hoping to see more of -- specifically, the lack any actual "Sith training" is an insane missed oppturtunity IMO, and could've been a cool way to flesh out the Sith and/or Dark side in general, while also serving as a sort of inverted version of Luke and Yoda in TESB.
I was also one of the people who (before the rumor was dispelled) would've actually not minded a Snoke-as-Plagueis twist. Despite the prequels being generally very poor movies, I do feel like there should be a little more continuity between trilogies. Beyond that, the notion of a reincarnating/immortal Force user whose been manipulating the galactic society for decades Dunyain-style has some potential in my mind (assuming it had, like, good writing and not another cackling, cartoonishly evil Big Bad), and it could've even helped handwave some of the series extant weird plot holes and/or lazy worldbuilding such as the similarity of the First Order to the Empire, or even why Kylo would decide to be trained by such an individual, given his Vader fanboyism.
Speaking of villains, the portrayal of Hux was borderline character assassination. I mean he wasn't anything amazing in TFA per se, but again, like Finn (or Rey, or Snoke) the character had plenty of potential for growth. Instead he became a receptacle for corny humor (because there wasn't enough of that already).