I honestly think season three is one of the best overall seasons of any Trek series. It's got good energy, and I've talked pretty extensively about why I think the ending is pretty great, actually.
killing Book’s family was kind of idiotic
The poor species was doomed once they were revealed to be spore drive-compatible. They were never going to take away the lead ship's unique feature.
Also, background character development feels a bit weak.
I've probably talked about this before as well, but I think Disco was pretty experimental with the extended cast - they essentially gave what would have been wordless extras on other shows and gave them a bit more to do.
Ultimately, I think it was a bit of a failed experiment, but at least some talented Canadian actors were able to pad their resumes.
I will say that S4 gets better as it goes along, and a lot of people would cite it as their favourite.