OK, so I finally watched the premiere a few days ago! Here are my thoughts:
All right, so I'm definitely sad that Ezra's taking steps down a dark path--_however_, it's being done really well, so I can't complain. The whole scene with him controlling the AT-DP Pilot was perfectly ominous, and that look he gave after it was over actually scared me. I understand his intentions--his friends have been hurt, and he feels responsible. Maybe dipping into the Dark Side isn't so bad, if it results in a greater good. But it's a dangerous path, and he's the kind of person most likely to be swayed too far by the allure of evil.
Speaking of evil, hooray for Thrawn! His introduction was interesting--very calm, and without much build-up. TBH, that actually felt more fitting than his introduction in the trailer. While that was--to use his words--"artistically done," this one felt more in line with his character, subdued but imposing. I almost wish I hadn't seen the trailer or heard the news of his arrival before I watched this episode--I would love to know what my reaction would have been to seeing him walk out of the shadows with Pryce, having no knowledge of what was about to happen. Other than that, I felt he was introduced well. Already we can see the gears in his head working on his master scheme, and it was great to watch Admiral Constantine get so befuddled when Thrawn told Pryce to let the rebels escape.
OK, on to other things. I was intrigued by Bendu and his scene with Kanan. I had heard reports that he was going to be more of an evil character--and him now possessing the Sith Holocron makes that a possibility--but I was glad that he served a more mentoring role at first. I also totally bought into Kanan's struggles with blindness, mostly due to Freddie Prinze Jr's. incredible acting skills.
The other characters kind of took a back door here, but that's OK, considering the entire season ahead of us, and the fact that a few of them (Hera and Sabine, mainly) seem to be stepping into more functioning roles this season.
The scene that really got me in this episode, though, was the scene where Kanan rescued Ezra. The symbolism was amazing, with Kanan--the character who is now forever "in the dark"--reaching out from the light to Ezra--who can see clearly, but is trapped in the darkness. That, combined with the well-placed use of the Force Theme, made the scene a very emotionally charged one. I think that as long as Kanan is around, Ezra will stay in the light. If Kanan dies, Ezra will almost certainly turn dark, even if he can contact Kanan's Force Ghost.
In general, while it might not have been as intense as last season's premiere (which is the best one simply because of Vader), this episode was a nice way of getting back into Rebels. It was cool to see how everyone has grown (I'm still not used to how tall Ezra is now), and I look forward to more of his and Kanan's inner conflicts--and, of course, Thrawn!