Why (was?) the Soviet economy during the Cold War era such a failure?

[robby]

@DrDeth

@FlikTheBlue

A spin off of the thread on what the Soviet Union did better than the west.

Link please.

Soviet technology that was on par with, or better than it's Western counterpart

It is pretty much a given that the West did most things better than the USSR, but were there areas, or technologies where the Soviet Union was ahead?