I just saw Awakens on the weekend, finally. It's an excellent movie. I'm a lifelong Star Wars fan - Jedi in theaters was the first film I've ever seen - and this movie is very true to the series and excellent in its execution.
The flaws as stated in the OP are completely false. At least they are false if you are a Star Wars fan. All the questions and loose ends and lack of back story? That's classic Star Wars. As a kid I can remember asking my brother "Who is Boba Fett?" "What is Darth Vader?" "Why can the emperor shoot lightning?" "What were the Clone Wars?" Most of this isn't really explained in the films, and almost all is not explained when first revealed. We know it now, it's all in pop culture, but on the first screening you don't. And I still don't know who the Shaman of the Whills are and how the whole Ghost Jedi thing works.
But that stuff doesn't really matter. Who the Knights of Ren are is irrelevant beyond there some bad-ass guys - though I'm sure we'll get more details at some point. The past of Rey is an obvious future plot point. So is Snoke. The early teases were classic JJ and classic Star Wars, which is why the two are a good fit.
Anyway, my take was it was an excellent movie and really captured the "feel" of Star Wars. It recycled a bit of stuff, some of which is OK. The single biggest flaw Starkiller Station. The device itself was cool, but the mission to destroy it at the end felt tacked on. I would have preferred the finale ended with the Station being a hidden mystery, desguised as a planet, a future massive threat to be revealed in a future film. Rescuing Rey and the duel at the end would have been good enough. And speaking of that duel, we a) really don't know the level of training Ren has and b) it should be obvious that Rey is special and more powerful in the Force than Ren. This was made apparent in their mind-reading duel earlier. And Rey didn't beat Ren "easily", Ren was actually taking it to Rey with her just defending. She managed a late comeback with some rage - and possible Dark Side influence. In the novelization she actually hears a voice saying "finish him" or something of that sort. If the Force can give look the ability to hit a target that no one else can hit, - and we know it gives super-human reaction time, the ability to see events before they happen, etc - it's not outside the plot to think it gives Rey the ability to fight off Ren. Also, she was already shown to be skilled in melee weapons and combat with a staff being her preferred choice.
All in all, an excellent, well filmed and acted movie, worthy of Star Wars. And if you don't like the unexplained First Order, etc, try watching A New Hope again, but removing any knowledge from your brain about the Empire, Rebels or Senate. None of it is really explained. That blank space is part of the magic. Like the black background in an 8-bit game, your imagination can fill in the details.