Who's on board, where the capsule is right now, and why the toughest part isn't the flight — it's coming back. On re-entry Orion will hit the atmosphere at extreme velocity in ~3000 °C heat and literally skip along its upper edge (skip-entry) to ease the g-load on the crew and keep the heat shield intact.
If you want to quickly get up to speed on the mission, see where the crew is, and watch their live broadcasts from lunar orbit — take a look at the special: