The short answer is—yes. Let's look at the evidence. First of all, Harding himself was critical of his administration. In a moment of candor, he admitted that he was unfit for the office of President and shouldn't have been in the White House to begin with.
Additionally, his short term in office was plagued by rampant corruption—most notoriously, the Teapot Dome scandal—which he did little or nothing to stop. While Harding's associates plundered the government's coffers, he preferred to indulge in his hobbies: golf, poker, and serial adultery. (His father once told him that, if he'd been a born a girl, he'd be pregnant all the time—as he wouldn't be able to say no). As Harding freely admitted, he could handle his enemies; it was his supposed friends who kept him awake at nights.
In the realm of foreign affairs, Harding presided over the beginning of a period of isolationism. During this period, the United States retreated from a position of influence on the international stage, helping to pave the way for the rise of fascism in the 1930s. Though Harding wasn't personally responsible for the mood of isolationism that dominated the country, he did nothing to challenge it. He argued that America should enter a period of "normalcy," characterized by a period in which the US didn't engage directly in foreign affairs, but rather looked after itself and its own interests.
On the whole, one would have to say that the historical consensus is absolutely right: amiable though he undoubtedly was, Warren Gamaliel Harding, 29th President of the United States, wasn't a good leader.