The more specific and longer version begins with the fact that I am droolingly jealous of McDonald's ability with language. I lost track of the number of times that I would stop and read a sentence out loud to better appreciate how perfect it was. McDonald's prose manages to be both rich and precise: detailed, with no superfluous words.
The story is of three Brazils: present, future, and past. It is also the story of the multiverse of layered Brazils, layered worlds, that exist. McDonald's choice to tell his story in a temporal triptych, where the events of the story unfold at the same pace in different times is an example of the form of the story perfectly complimenting the kind of story that is being told. The multiverse is always happening. I also found the ordering of the stories - always present, then future, then past - to be very effective. It was a powerful method of conveying that all events are being influenced by both what comes before and what comes after, that time is a loop, not a line. (This would be the point, yet again, where I mention how jealous I am of McDonald's skill as a writer.)
Brasyl is also full of rich and interesting characters. I was most impressed by Fr. Luis Quinn, a Jesuit in the Brazil of the 18th century. I went to a Jesuit high school, and I've done the spiritual exercises of St. Ignatius Loyola, so I feel like I have a pretty decent grasp, for a laywoman, on the Jesuit psyche. Fr. Quinn is a Jesuit, from his fascination with languages to his continual prayer that God might give him "a task most difficult." Fr. Quinn is also a swordsman, and McDonald nails that detail, too - Quinn sees with a fencer's layered awareness for detail, even before... well, I won't spoil the details, because trust me, you'll want to read them for yourself.