I thought it looked disapointing in the middle of the day, but come the evening and the colours before sunset it was stunning. Suspect that from a plane it would look diminished unless you actually fly into it rather than above it, I have no idea if the tourist trips do that, and if they do I would get scared flying in it.
It is awful easy to misjudge walking down into it as unlike normal walks you go down first and then up - it's easy to find you have overreached yourself. As someone else said, take water - there isn't any on the way down. You could instead take a mule ride into it.
There were lots of free talks on when I was there including ones about the condors, and the fossils exposed in some of the rocks. Recomended.
However it is a bit of a tourist trap!