I have answered a similar question here. In some detail.

In short Cadorna was a somewhat poor choice for a Chief of Staff, but for other reasons than those usually cited. Cadorna had a solid theoretical background - albeit a rather old fashioned one - and was generally competent in his conduct of the Army. Despite the poor state of the Army and the logistic nightmare that was Italy's mobilization, he had managed to put together a coherent force by 1916, involved in some successful offensive operations - despite the common myth of the twelve pointless battles of the Isonzo River. He was sustained by a strong moral sentiment, efficient and energetic, to the point of his own detriment at times.

At the same time, his obstinacy, his over reliance on discipline, his rigid sense of honor and personal duty led him to a consistently negative attitude towards the men, and (with very few exceptions) his own staff - he remained infamous for the incredible number of high ranking officers sacked or demoted, but among those there were many who had made their ranks out of thirty years of seniority advancements - as well as suspicion towards the political world that made cooperation among the two powers a matter of constant frictions.

His treatment of the men was often distant to the point of callousness - and he did advocate (and give explicit instructions) for the use of summary executions as a mean to maintain discipline.

It was his sacking after the defeat of Caporetto, and the subsequent inquest that largely targeted his conduct of the war, that gave rise to the idea that Cadorna was especially bad at his job. He wasn't that bad - and he was far from great either.

After the Italian victory, the matter of the responsibilities of the High Command for Caporetto were largely swept under the rug and Cadorna could enjoy some form of popularity as the Commander in Chief that had led Italy to the Great War. Those recriminations continued to exist though, tinted with political conflicts among those who had wanted the inquest and those who were content with the idea of the "military strike" caused by the socialists - a view that Cadorna himself supported at first, and appeared to believe, since a failure of discipline and motivation could be the only possible explanation of the disaster.

I think it's telling of Cadorna's approach to command - and of his limitations, despite his positive traits, that indeed existed - that he saw a crisis of discipline and morale among the troops as something that should be blamed on the troops, rather than on his own method of command.

With the end of the Fascist Regime, a certain thread of national-patriotic literature of the Great War came to be widely - and deservedly so - subverted. But this fact has often created somewhat of a vacuum around certain figures and events, as well as a likely irreparable draught of information on certain details of the military operations. So that the old national-patriotic narrative has often been replaced by a sort of anti-national-patriotic narrative, that is Italy's own version of the "lions led by donkeys", with Cadorna being the Donkey in Chief. A label he doesn't deserve - while I'd argue that he offers enough points for a more substantial and legitmate criticism, which has the added bonus of providing a better understanding of the general conduct of the Italian war, and of the limitations of the Italian establishment in their approach to the conflict.

This is just a short summary though! Check the answer and feel free to ask for clarification.