The Three Body Trilogy is actually one of my all time favorite scifi book series (and I read a lot of scifi). A lot of interesting ideas are developed through the story arc. Perhaps unfortunately, the first book is more setting the stage for the others, which makes it a difficult read for some. The Three Body Trilogy IMO would probably have better merged into a single book, but then doing so would make it seem an impossibly long read for some perhaps. I agree it is a bit slow at times, but worth it.

If you want a denser read (less setup, etc.) that also has a lot of really thought-provoking concepts, I highly recommend also "Blindsight" by Peter Watts. Blindsight is probably my all time favorite scifi novel, actually.