I love this show, but I didn't like the Mirror Universe story arc at all.
Captain Lorca was a very interesting character, possibly the most interesting character on the show after Michael Burnham. Now they've completely destroyed the character. The character was destroyed long before Emperor Georgiou stuck a spear in him. He went from a complex and interesting character to a complete caricature. Now he's just some evil duplicate from a parallel universe who got himself killed trying to execute his dastardly plan to take over the Universe (his Universe, anyway).
I'll admit that for 30 seconds after "the reveal" it was shocking and interesting, but after I thought about it, it made no sense whatsoever. How did the Mirror Universe version of Lorca wind up as a Star Fleet captain anyway? Did he find his counterpart, kill him, and take his place? It sure as hell seems like he had a lot of resources at his disposal after he was abruptly transported into a completely different universe by a freak ion storm.
I just thought the whole idea early on that Burnham was a disgraced "traitor" who beat the odds and worked her way back to be a respected Star Fleet officer was a very interesting story. Now we know the only reason Lorca pulled strings to get her out of prison and put her on his ship was was because he enjoyed boinking the Burhnam from his universe, and he thought he could trick her into helping him pull off his dastardly plan.
It was totally contrived. It was the epitome of the Deus ex machina plot device. Plus, for good measure they threw in the totally ridiculous and unnecessary subplot that the contamination of the spore drive's mycelium network was about to destroy ALL LIFE IN ALL UNIVERSES! It sure was lucky that they could prevent the destruction of the multiverse with a couple of well-placed photon torpedoes.
I'll keep watching this show to see what they do going forward, but I absolutely ****ing hated this storyline. I assume now they're going to find the real version of Lorca alive and well, and they'll probably install him as captain of the Discovery. That won't make any ****ing sense either.
The Mirror Universe was great for a single episode on the original Star Trek series. Making it such a major part of this new series is a horrible idea.