Liked it a lot. A 9 for me, and not in any way filler. It didn't rise to the level of the best this series has done, but it wasn't going to--it's set up, not pay off.
I'd go so far as to say that the show would have been narratively irresponsible if it didn't have a longer, slower episode to address the many character moments on which our investment is going to be built. We got commentary on Ash and Michael, Cornwell and Lorca, Michael and Georgiou, Sarek and Michael, Sarek and Georgiou, Stamets and Ash, and even evidence of character growth for Tilly. We saw Detmer and Bryce edge closer to being fully fleshed out characters. And we finally get to see why those first two episodes of the show were so important to the whole story where at first they seemed like a slightly odd prequel (at least to me, though I liked them).
I wasn't sure at first if I bought that they'd put Georgiou in command (with oversight, I imagine), but hey, the last mirror person they installed on Discovery got them a big advantage in the war, and they're damned desperate. I think I buy it, and it certainly sets the stage for the biggest challenge to Starfleet ideals we've yet gotten, which looks to be the crux of the finale.
Tangent: I'm interested by the Greek and Roman mythological notes this show is dropping, including Virgil and Charon. There's something Achilles and Patroclus-esque about where we find Stamets and Culber. We've been to the underworld and back...who knows what comes next?
Edited for words.
