When pushing the envelope, anything better than catastrophic failure is success. That an engine exploded and both primary and secondary missions were still completed is fantastic.
Rocketships are insane, there has to be many many fail safes because failures happen all the time. I remember a NASA engineer giving a talk on engineering safety when I was going to school where he said that the probability of catastrophic failure in NASA's launches is 1 in 100 and that is as low as they are able to make it at this point in time.
Closer to 2 in 100: 2 shuttle losses in 135 flights, plus 1 catastrophic failure out of 32 missions in the pre-shuttle era.