The launch was successful, so was delivering the payload and landing the boosters. But core landing failed spectacularly. It was a hard job nevertheless. And spacex hasn't landed a core successfuly yet. This probably was its first try.
Video of today's crash
https://www.youtube.com/watch?v=nxUuEHWJtlQ
https://www.youtube.com/watch?v=nxUuEHWJtlQ