Spanish inquisition's brutality, while true if we judge it by modern standards, has been wildly exaggerated, mainly for politico-religious reasons. This vilification of the inquisition forms part, more generally, of the so-called Black Legend, a collection of narratives popular in protestant Europe that depict Spain, the main Catholic power of the time, as the epitome of evil and barbarism. What those narratives often forget to mention though, is that torture and persecution of Catholics, and other suspected heretics, was common in protestant Europe as well (think for example of witch burning).

Nowadays there's a revisionist trend that has tried to dispel some of those myths, and to give a more nuanced understanding of the Inquisition. Kamen is the best known Historian in the English language language that works on this subject I can think of (Check his book) . For example, the use of torture was not as widespread as commonly thought (it was restricted to the interrogation) and it forbade maiming or spilling blood:

"As with all European tribunals of the time, torture was employed. The Spanish inquisition, however, engaged in it far less often and with greater care than other courts. Historian Henry Kamen contends that some "popular" accounts of the inquisition (those that describe scenes of uncontrolled sadistic torture) are not based in truth. Kamen argues that torture was only ever used to elicit information or a confession, not for punitive reasons" link ^(this wikipedia article summarizes some of Kamen's thesis. Do check it out)

The Inquisition also gave, at least theoretically, safeguards for the accused, and required the heresy to be established before court respecting some form of 'due process'. In this way, it prefigured some aspects of modern criminal law. Also, only a fraction of those accused were ultimately sentenced to death. In Italy, Andre Del Col estimated that only 2% were.