This was the episode I was most excited about when the titles were announced. "Unification" and "Unification II" made up a major two-part episode of The Next Generation, bringing Spock into the series and beginning his (and by extension, Picard's) involvement in Romulan society and the beginnings of reunification between Vulcan and Romulus. It was almost inevitable that Vulcan and Romulus would be united in the far future, especially after Romulus itself was destroyed. I was also looking to the inevitable scene when Michael found out what her brother got up to after she left him, and the look of shock when she found out what a legend he was didn't disappoint.
There's a few moments that take the biscuit when it comes to believability. With the knowledge that the Federation has lost most of its members, wouldn't Saru and Burnham have looked up the situation and seen who was still involved? Equally, I can't believe that no one thought to mention the SB-19 experiment and how Vulcan was convinced it was the cause of the Burn. I know that Starfleet have dismissed the idea, but surely it was worth pointing out to the woman who had made it her personal mission to solve the crisis?
Still, accepting all this, I love some of the details. Of course, Saru and Burnham aren't aware that the Romulans and Vulcans are related, and still distrust the Romulans. I love that Burnham is convinced that the Romulans are the ones who forced the Vulcans to leave the Federation, when actually it was their idea. All of this ties back to TNG, where we first encountered not only the reunification movement but also Vulcan separatists. It's not all blatant stuff like a clip of Spock from "Reunification II" and Michael's mum turning up (more on that in a minute); all the elements of the episode act to tie disparate parts of the franchise together, in a remarkably fluid and non-fanwanky way.
The journey to Ni'Var, the planet formerly known as Vulcan, is an exciting prospect, so it's tremendously disappointing that we never set foot there and this is left as a bottle episode set on Discovery itself. We get to see different factions of Romulans, Vulcans, and Romulo-Vulcans (mixed race people, I guess) at the logical talk-off the t'kal-in-tet, but there's never a real sense of place. Bringing in the Qowat Milat, the truth-speaking ninja space nuns from Star Trek: Picard, is another nice touch.
Again, it stretches belief when, not only are the Vulcans impressed that Burnham is there (how the hell do they even know who she is? I know she's the most important person in the galaxy but that was meant to be kept on the downlow), but her mum is now part of the Qowat Milat. It leads to a very nice scene where Mama Burnham uses her powers of absolute candour to put Michael on the spot and actually admit what's driving her these days, but it's still an absolutely ridiculous coincidence. Then again, adventure fiction is full of such contrivances.
The other major element of the episode is Tilly being made Acting First Officer, which is also absurd but works dramatically. Of course it has to be Tilly, who is the heart of the series and the crew. It's ridiculous in realistic terms, since she's the lowest ranking member of the crew, but then, we do know that Saru is a big fan of Captain Pike (he did promote Kirk to Acting First Officer in the other timeline, and that was straight from cadet). It's silly, but it works in terms of the series, although I would like it if Admiral Vance has a word or two with Saru.
There has been some comment that, for all the talk of exploring a bold new future, there's been a lot of time spent on reworking the franchise's familiar elements. We've seen 32nd century Earth, Trill, the Andorians and Orions, and now the Vulcans and Romulans, so this is a fair criticism, but there's good reason to explore how the major elements of Star Trek's "present" have changed over the centuries. After this, we've only really got the Klingons to go as a major culture to explore (although there's mileage in the Ferengi, Cardassians, Borg and Dominion as well), but it's important to the overall story. Nonetheless, after 900 years, having a minor or completely unknown race in a major position of power would be more satisfying.
Regardless, Vulcan's future is an essential part of the Star Trek story. As long as you can accept the absurd level of contrivance, this is a satisfying episode, even though very little actually happens in it. It fills in another vital element of the new future, with a powerful emotional story along the way.
The name Ni'Var is an astonishingly deep cut bit of fanlore. News to me but a really clever callback. It had previously been used as a Vulcan ship name on Enterprise as well.
With this episode, the Romulans join the Vulcans as one of only two alien races to appear in every Star Trek series (unless you count Short Treks as a series, in which case the Romulans and Klingons are joint with a series each to go).
No one mentions the Romulan supernova, nor that Spock tried to stop it (and is presumably recorded as having died in the nova). Even on Picard no one mentioned Spock's involvement in the supernova crisis; presumably there's a rights issue regarding the material from the reboot films.
Why were the Vulcans experimenting with a dilithium replacement when the Romulans have been using quantum singularity technology for centuries?
If the t'kal-in-tet has been used since the time of Surak, that puts it at around 2800 years old.
There's a moment when Tilly points out space is three-dimensional. Characters in Trek seem to need reminding of this surprisingly often.
It's impossible to use a microscopically small time variance to triangulate events when dealing with astronomical distances. Time isn't constant, and over light years the variance could be enormous. But then, if we think along those lines, warp travel causes all kinds of problems of causality.
After the USS Nog two episodes ago, this week we hear of the USS Yelchin, named for the late Anton Yelchin. My emotions can only take so much.
Other starships mentioned include the USS Giacconi, presumably named for Riccardo Giacconi the astrophysicist, and the Gav'nor, which sounds likes a Klingon ship (or possibly cockney).