All it had to do was slow down in the last phase and land. It's not like a Harrier jet. After the entry phase, heat shield, and parachute deployment, the entry vehicle had to fire rockets to slow down to a stationary position, after which point it drops the actual rover by cable, then charges blow the cables and the thing crashes. All in much lighter gravity. They've done it the same way a bunch of times now. It's actually a pretty crude method and doesn't seem that difficult to me. It's not the same as a VTOL craft using rockets to take off and land all the time.