So, I'm a good public for this I suppose, since I loved Mamma Mia, and am a real fan of rock/metal operas. And I think this episode is... surprisingly decent?

I mean, the singing was surprisingly good, even with autotune (I mean, if you ever want to hear a real musical disaster, try Pierce Brosnan in Mamma Mia ; everyone here is pretty much excellent compared to that), so kudos to crew. The music was uneven : some parts were quite bland/uninspired, but I very much loved the common theme of "I'm ready"(catchy!)/"I'm the X"(lovely!) and the two widely different feelings.

On the plot side, you can feel they are trying very hard to brush over how nonsensical this musical thing is. And, somehow, I'm glad that not much progress happens here : you can summarize what happens as "La'an tell Kirk about the time-travel event, Spock gets dumped for a study program, Pike have a minor fight. And musical subspace shenanigans.", which will sure come in handy if you're allergic to musicals and (re-)watch the series.

But yeah, it was fun. The "La'an cut the captains couple argument in the middle of signing", and the boys-band/K-pop klingon were unexpected.

Overall, I think this episode somewhat suffer the comparison with the Lower Deck crossover. The s02e07 was a real Star trek story : if Lower Deck wasn't a thing, "These old scientists" would still be a decent story, it's the meta element which push it into the land of deep sillyness (even when, like me, you don't really like Lower Decks). "Subspace rhapsody" is... a musical. It's good fun! But I was hoping for a bit more.