[Vince Ferrer]

This is an excellent accomplishment. There has never been a more thorough test of an escape system on a launch vehicle. The Apollo rockets had a similar system, but it was only tested on the ground. The dragon capsule was also ground tested a couple of years ago. The shuttle could do some aborts to land on runways, but there were gaps in the launch where that wasn't possible. As a we have seen through real flight failures, the shuttle could not survive an explosion. Only blue origin has had a similar test to separate while launching, but that was a suborbital launch

So with this test the Falcon + Dragon went from untested to being the safest launch vehicle ever.

Here is a good analysis by Scott Manley, who is a very good blogger on space issues. (Much better than the typical science reporter in the mainstream press)

SpaceX Explodes A Rocket To Show That It's Safe

[Eric Pode of Croydon]

The Apollo rockets had a similar system, but it was only tested on the ground.

Not quite correct.

The Apollo spacecraft had an escape tower, not internal rockets like the Dragon. And the Apollo escape tower was tested several times in flight using the "Little Joe II" booster.