I thought that one was...fine. A perfectly acceptable unit of Star Trek.
I probably would have found it more interesting if Moll and L'ak had been the main protagonists of the episode, spending more time with them on the Enterprise in addition to their flashbacks, with Book and Burnham as the antagonists of the story.
On the other hand, I enjoyed Rayner's B plot, so maybe not.
Edit: and pour one out for our man Rhys, famous Constitution class fan who doesn't get to go on the mission to deliver the Enterprise to Federation HQ.