Ok, a post from someone that really hate musicals and was worried about this episode. So sorry if I will over criticize the episode...
I admit the episode was so fun at the beginning and songs were nice, loved La'an and Una parts they were really good. I was thinking the episode was a banger. I loved so much the opera opening too.
Unlikely it started to lose my attention around on Chapel's song (also because the autotune was so evident in her and I found the Chapel Spock relationship the worst part of the series) and the second part was a little hard for me to follow, the music too was less interesting and even if Uhura has a great voice her solo song was too long and def not my cup of tea, I didn't even understand what was trying to say. It could have worked for me with less songs.
It was interesting I have fun for more than I thought and I laughed so much with Klingons, it was often close to clinginess but it was ok at the end.
My biggest gripe with this episode is
spoiler
that it could been easily a double episode THIS SEASON with more breath, I hate those cliffhangers but the plot armor was too strong here, we already know who will survive and who don't even before the start of the episode xD
I expect we’ll see Sulu, McCoy and more Scotty next season:::