At an absolute minimum this flight has shown that SpaceX is capable of testing reuse of the first stage on operational launches (including use of landing legs on the first stage) with no impact to the launch (provided there is sufficient payload margin, which there will be on any further Dragon launches). That's a big deal, it means they get tens of millions of dollars in free testing subsidized by their customers, and that gives them a huge leg up in working towards reusability.
>>Inclin+(OP)
As of about an hour ago, this flight has also shown that they can successfully do a powered landing of the first stage. This has been one hell of a good day.
>>Inclin+kp
Well, the original plan was to use several :-D smileys to convey the well-deserved breadth of my grin, but when I typed them all out they looked tacky.
... Ah, to hell with it. A modified Falcon 9 rocket stage did a powered landing for the very first time. Eventually this could cause launch costs to plummet, and open up space in earnest. EEEEEEE!!!! :-D :-D :-D