Well one of the problems with the big engines NASA was using was getting the fuel in fast enough. They did this by fitting big pumps. Apparently the Russians used a turbine powered by the rocket to achieve it, something NASA said wasn't possible. It saved weight and gave more thrust. What the Russians couldn't do was make stuff well.
It wasn't used much though, other rockets don't have a much worse failure rate, not even the shuttle. They cancelled the last few Apollo missions, partly to avoid an accident, they knew they were pushing their luck.