The following is an excerpt from the Ars Technica article:

Among those eagerly watching the flight tests was Bobby Braun, an aerospace engineer at Georgia Institute of Technology, who has led a joint research effort with SpaceX and NASA to study supersonic retro-propulsion. "I have access to all of that data, and I’ll tell you that it's worked like a charm every time," he told Ars. "The stability was manageable, and while there are still some issues, there are no showstoppers."

The full article can be found here.