I'm really new to the Cosmere as well. I recently tore through the 6 books and enjoyed them all. I would say that the first trilogy is masterful in its plot, action, and twists, while the 2nd trilogy feels a bit more lighthearted or silly, while still giving essential knowledge for the cosmere. I agree that it is fun to watch a developing society incorporate the planet's magic system; the setting of the second trilogy reminded me of something like the industrial revolution or steampunk, but with allomancy. Pretty cool imo