I really liked season 1. Lorca was a great character. Mirror universe is overdone, maybe, but that didn't bother me. The major failing of S1 is they set the stakes too high for the climax. "We have to stop the bad guys or it's the end of the universe." Well guess what, I've seen TNG so I know the universe didn't end here. Way to kill the tension.
What they should have done was put the mycelial network at stake. Since it never shows up again I would have credibly believed those stakes.