Yesterday's 10M Siege of Orgrimmar PTR testing on Normal difficulty has revealed two new encounters. So far, the bosses look promising and much easier than Throne of Thunder encounters. Every encounter in the Siege so far seems to have unique mechanisms.
Blizzard's encounter designer Watcher has said that the Iron Juggernaut encounter should last about 8 minutes. The health has been increased artificially to test out the abilities properly. Here's a video of a player from Drak'thul talking about the mechanics:
Sha of Pride
The seventh was also part of the testing yesterday. To see more of her abilities, view the video below.