It was an unmitigated disaster that ended in hyperinflation. The fundamental problem was that each country had a central bank that issued ruble credits, because no country was prepared to accept central-effectively Russian-control over its monetary policy.
Ningún país de la CEI aceptaría un monopolio ruso sobre la emisión de una moneda común, y sin un monopolio central sobre la emisión de dinero, una unión monetaria no puede funcionar.