Tupiza - Oruro is a hectic mountainous section. A lot of passes, aretes and riverbeds could be in the mix. Oruoro - La Paz even more so, the scenery there is very, very wild with massive snow capped mountains etc. That stage I bet will have some hill climbs of note like we saw a couple of years ago in Argentina.
La Paz to Uyuni is much flatter and will have dunes and riverbed sections as well, and of course the famous Salar de Uyuni, the biggest slat flat on the planet.
Uyuni to Salta will likely have the Lago colorado (which is a bright blue lake) and volcanoes that the guys will be going past. Should give us some really spectacular footage.
Weather at this time of year is really hectic especially for the first two Bolivian stages, its quite possible that one of these will be cancelled because the birds will unlikely be able to fly.
It will be interesting to see how they managed on the legs back from La Paz, because all of the terrain is above 4200m, which helicopters dont like.