I'm having a really hard time wrapping my head around your question. What do you mean by the GLF? If you're just talking about the period from 1958-1962, the GLF was an unmitigated disaster. Tombstone makes for incredibly chilling reading. On the other hand if you're talking about the post 1949 centralized economy in general there were definitely very real gains in output and standards of living up to the GLF. Leading up to the GLF, there were debates between pragmatists (Zhou Enlai, Peng Dehuai, etc.) and idealists (Mao and many allies at the provincial and local level) on economic policy. For a time the pragmatists had an edge but Mao eventually suppressed opposition to the GLF (a term that was actually coined by Zhou in a bit of intra-party diplomacy) and threw the country into an utter catastrophe. I suppose if you take the long view you could argue that the twin disasters of the GLF and the cultural revolution set the stage for a turn away from radical idealism and planned economies altogether by Deng but that's kind of speculative.

There really weren't any positives, as flyingdragon8 points out it was an unmitigated disaster.

For an example, Mao decided that since first rate nations made steel then China would make steel. He got together with some non-engineers and decided that peasants could make steel in homemade blast furnaces then sent out orders and instructions. The local leaders didn't want their numbers to look bad so they melted down whatever iron and steel could be found and sent it on.

The result was a mass destruction of necessary farming implements which in turn contributed to the massive famine.

Another example would be Mao's government setting production quotas for farmers, vastly higher than could be realistically expected, because they believed that with proper leadership and communist go get it done attitude the peasants could easily double or even quadruple their output.

Local leaders didn't want to look bad so they reported back to the government that they were meeting, or even exceeding, the grain production quotas.

Then the government came and collected the grain based on reported production leaving nothing for the farmers to eat. This, as you might imagine, contributed to the famine.

And there was the eradication of the four pests, which were defined as rats, flies, mosquitoes, and sparrows. The first three are genuine pests and dangers to humans, and of course difficult to kill. Sparrows were included because they sometimes ate grain and were therefore stealing the fruits of the PRC's labor.

What any biologist could have told them, if they'd asked, was that sparrows ate a very little grain, and a lot of insects. And, of course, unlike the other pests, sparrows are very easy to kill. So easy that they were pretty much eradicated in most of China. As a result, the insects they fed on multiplied in vast numbers and ate a LOT of grain thus starting the famine previously mentioned.

Overall it is estimated that around 20 million Chinese starved during the Great Leap Forward, mostly due to incompetence or outright foolish action on the part of the PRC government.

Like the Cultural Revolution, the Great Leap Forward was as close to a complete disaster and utter catastrophe as any organized human activity has come. The result was the devastation of many critical ecosystems, mass starvation, and setting back China's technological development. Essentially it produced the exact polar opposite of what the PRC wanted to produce.