Now that the season is over, I signed up for my three-day free trial of CBS All Access and marathoned the whole thing in three days. I gotta say, I did not find any of the Klingon War storylines interesting at all, with the lone exception of Voq and L'Rell. And even their story was totally run aground with the whole genetic engineering Voq to become human angle, a twist which I thought landed with a big ol' thud. Voq and L'Rell worked great as a couple, but once they were separated in order to service the plot, neither of them worked for me as characters anymore.
The Mirror Universe storyline, however, I thought was incredible, and I think this really should have become the focus of the entire season, if not the entire show. That caught me totally by surprise, as did the subsequent twist relating to Lorca. When that whole story line was coming to a head, I thought to myself "Wait, how are there two episodes left? I can't wait to see where this Mirror Universe stuff goes next, because I have no idea where it could possibly go after that!" Turns out it was just going right back to the Klingon War again, which seemed like a huge step backwards. As a viewer, I had totally stopped caring about the Klingon War, especially given the fact that this is a prequel and we know how it turns out. Honestly, when whats-his-face the red face paint Klingon leader died, I kinda thought that meant the war was over. But nah, that just meant that "Now we're fighting 24 enemies instead of one, this is so much worse than an organized front somehow!", which is maybe the dumbest thing I've seen in Star Trek since Spock lost his brain.
I do think the cast of characters was really, really strong. That's something that always put me off of all the post-TNG series, that while I do think each show's captain is generally very well written and acted, the supporting casts of some of the lesser Star Trek series tend to be incredibly bland, in my opinion. Weirdly, Discovery almost has the opposite problem: incredible supporting cast, but I wasn't all that into the preposterous amount of turnover in the captain's chair. What was the final count? Something like six people end up commanding the Discovery by the end of the series? Including one cadet, one admiral, and one emperor from another dimension? It was almost comical by the end. But even so, I loved the crew, and I thought even the smallest supporting player was really well defined and interesting.
Also, I'd be curious to know, from folks who know Star Trek better than I do (I love the TOS and TNG crews, but really can't get into anything beyond that) if Discovery is consistent with Trek lore, particularly Star Trek: Enterprise. I'm vaguely aware of the fact that Enterprise gets into the whole Klingon genetic manipulation retcon which explains their appearance in TOS, but Discovery seems to imply that this is the first time they've attempted it, which didn't seem to line up with me. Then again, I'm about as far from an expert as they come.
Also, I could not have rolled my eyes any harder at the appearance of The Enterprise at the end. Honestly, stuff like that reeks of desperation to me. A confident show doesn't need to do that.