Say what you will, he seemed a politician very keen on world peace, beyond mere lip service. He understood the lacunae of the Soviet system and genuinely set about to reform them. But ultimately it was Ethno-national interests in Ukraine, Baltics and Central Asian republics along with the rise of opportunist power-grabbers like Yeltsin that did him and Soviet Union in.
And perhaps his own reluctance to follow the Chinese model. He prefered to do political reforms before economic ones, while the Chinese prefered the economic reforms first and foremost.
He ended the war in Afghanistan. He was more keen on Nuclear disarmament than Western leaders: Western leaders dragged their feet on that matter, and ultimately we didn't get no where near Nuclear disarmament.
He ushered in reforms. See the Soviet films of the period to see a very different picture from cold war era Hollywood depictions.
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