For a machine as complex as the Saturn 5 rocket, it is truly a credit to the builders that it never suffered a major failure in any of the manned missions. Same for the LM rocket which returned the astronauts to the command module. Both had to absolutely work and both did.

As John Glenn quipped "It's a very sobering feeling to be up in space and realize one's safety factor was determined by the lowest bidder on a government contract."