Overall, I thought it was fine. I think it got hit a little harshly by critics. It's not terrible (read: unwatchable), but it's pretty firmly my least favorite Star Trek series.

Without actually looking through the full episode lists, and just going off what I remember of each season, here are my gut ratings:

S1: 3/10

S2: 5/10

S3: 4/10

S4: 8/10

Overall: 5/10

Going a bit more into my thoughts in each...

Season 1 - 3/10

Pros:

• First new Trek in a while.
• Neat graphics.
• Great cast. (Especially Doug Jones as Saru).

Cons:

• Prequel-itis...
• New graphics don't match the TOS era.
• We already know, roughly, how things will pan out.
• Retcons.
• Unintelligible Klingons (and unreadable subtitles).
• Discovery is ugly.

Season 2 - 5/10

Pros:

• Interesting season-long mystery, with payoff for multiple story beats.
• Introduces Anson Mount as Captain Pike, leading to the spinoff of Strange New Worlds.

Cons:

• More prequel-itis... ** Puts legacy characters in peril, when the audience knows they canonically must survive. Saps any tension. ** Galaxy-level threat must obviously be defeated, since we know there's life in the future canon. ** Burnham time suit well beyond reasonable tech level for the era. ** Control drone fleet tech unreasonable for the era.
• Predestination/Bootstrap paradox.
• Discount Borg.

Season 3 - 4/10

Pros:

• Finally out of prequel territory.
• Cool future tech.
• Interesting mystery of The Burn.
• Great character development.

Cons:

• Unsatisfying conclusion to The Burn mystery.
• Tired of seeing The Federation in shambles.
• Seriously, the source of The Burn was stupid.
• Discovery would be able to solve so, sooo many problems in this era.
• Did I mention the sad kid causing The Burn?

Season 4 - 8/10

Pros:

• More character development.
• Federation starting to get back on its feet.
• Interesting mystery around the "Dark Matter Anomaly" (DMA)
• We get to see The Federation deal with a truly alien first contact. Species 10-C was amazing.

Cons:

• Once again, an existential threat. Very exhausting.

Conclusion

I think Discovery suffered from one main issue, in multiple way: season-based plots. Since every season had a single main plot, any issues with the plot ruin the whole season. We don't get standalone great episodes like in the old series, which you could watch at random. You kinda need to watch the whole season. Furthermore, since each season had to have a big plot, every season is dealing with a huge issue. It's exhausting being in an existential crisis the entire time. That's the feeling we have in our real world right now. That's the reason I watch Star Trek; it's a glimpse at how the future might be brighter. Discovery never felt like a promising future. It felt like we are going to be struggling for our lives for the next millennium and more.

So, I still enjoyed it as a piece of media, and a part of the Star Trek canon, but it's not a show I see myself watching again and again like the rest of the franchise.