Were Mikhail Gorbachev's policies of reform successful ones?
That depends on what barometer you are using to determine success. Since Gorbachev did not intend to dismantle the Soviet communist system with these reforms, I guess you could say they were very unsuccessful from that point of view. The truth was that the communist economic system was not reformable, it was fatally flawed from the start. Only iron-fisted dictatorship and fear had held it together thus far.
However, if you look at the Russian economy today which, while still somewhat limited on the world economic scale, is much healthier and more productive than it was under communism, and Gorbachev's reforms not only helped ordinary Russian to realize this, but it began the process by whch revolution would come. So in the long run, they were successful in that vein.
Perestroika, then, was successful at demonstrating Soviet economic weaknesses and leading more people to want something different. Glasnost allowed them to express their desire for something different as well as release all the pent up frustration and anger of Soviet citizens over their economic and social suffering. It was pretty hard for Gorbachev to put those genies back in their bottles. And it did little to save communism in the USSR.