obviously spoilers ahead:
It wasn't a bad episode. I can easily say I enjoyed it, more so than a couple past episodes. Out of the three premiere episodes, it certainly wasn't the best but it was decent.
The villain was a bitter disappointment. I pretty much knew Sombra was the villain of the episode, but I wasn't expecting such a weak character. It was a bit surprising. The other disappointment was that Twilight was so focused on the test.
Other then that, the music was lovely (the songs were mediocre, imo). The foreshadowing is tearing me apart over here (WHAT WAS THE loving BOOK). Several things will occur later in this season related to this episode for sure.
I'm still excited for the rest of the season. For the first episode without Faust, they did a decent job.