Actual history shows that Qin Shi Huang was a despotic tyrant that killed millions
Said history was written mostly by the Han dynasty that followed him and was very interested in making a statement on why exactly the Qin dynasty was so evil and corrupt that it had to go and that they totally weren't making their own powergrab. The first emperor was brutal, but not outrageously or especially so by the standards of the time (for context this was around the same time Rome obliterated the cities of Corinth and Carthage from the face of the earth). All in all his rule was almost certainly more good than bad.
But what about the mass burial of scholars?
The majority of the people buried were not scholars but
fangshi, essentially so-called oracles, magicians, and charlatans that preyed on common folk and officials alike. Most of the hostility towards Qin from the Confucians was a combination of provincialism and being at heads philosophically.
But what about the book burnings?
Qin's burning of books isn't good but it also wasn't actually special. Qin had burned books that were deemed dangerous or morally suspect since the time of Ei Sei's grandfather. He also didn't burn any books with technical information, essentially the ancient equivalent of STEM subjects plus some philosophy, and kept a copy of all burned books in the imperial in case any of them were actually useful, but those were lost when the Han-Chu contention put the entire capital in flames. For some reason Liu Bang and Xiang Yu don't get any shit for it.
But what about his tyranny?
The actual legal codes we have found are basically not much different from Han legal codes. Qin may have been relatively strict, but that was only in comparison to the extremely ineffective feudal governments of the Warring States period. Feudal governments are infamously worthless at actually enforcing any of their laws. Qin's reputation for tyranny isn't completely unearned, but an actual legal code that got enforced (i.e. "rule of law", the main argument of legalism) is going to look tyrannical to people who were previously either untouched by the central government or believed themselves to be above the law.