I'm still amazed that it succeeded. I was prepared to bet quite a bit of money that at least one of the many quite complicated stages of the landing would fail. I'm happy I was wrong.
To me, the air bags[1] used to land the Spirit and Opportunity rovers seemed like a saner way to go than trying to deposit them gently directly on to the surface using a sky crane. The reported reason the sky crane was used for Curiosity is that it was too heavy for the air bag approach.
But the Spirit and Opportunity EDL also involved retrorockets in addition to a heatshield, a drogue chute, a parachute and the airbags - it's just that the retrorocket part didn't have to be as precise as with Curiosity.
[1] - https://www.youtube.com/watch?v=XRCIzZHpFtY