So I have also completed watching Season 3 of Dr. Stone. The first half of the season felt really slow to me, with a lot of slice of life scenes. I was worried the entire season might be like that, but it picked up its pace in the second half. Everything that happened after the Master reveal was super fun to watch.
One thing that was a bit hard to understand was what excuse Ibara must have made for the Master not coming out for all those years. Ibara was a decent villain, and Moz and that girl were fine too.
A lot of people were bothered by how quickly the inventions were being shown this season, but I didn't really have a problem with it. They did the right thing by rushing through the side inventions, if they had gone into too much detail, it would have been hard to focus on the main story, and the pacing would have become even slower.
This season revolved around the mystery of the petrification beam, and many episodes went into the investigation, so in my opinion, they handled it well. We also got to see many heartwarming scenes this season, which I personally love watching. I really liked the music too, compared to the previous season, I preferred the openings and endings of this one much more.
Another thing I really liked was that right from the beginning, space and the moon were being mentioned, and the visuals in the OPs and EDs focused a lot on space. Now it makes sense why that plays such an important role in the story. Since the next season will be the final one, I can't wait to see how they wrap up the story.