Compared to?

And how are you measuring 'brutality'?

I would say it was. Prior to Genghis the Mongols had generally been involved in warfare against other Mongol nomadic groups, so while undeniably brutal there were not any massacres or sackings on the scale (large city level) seen in the Mongol conquests.

Prior to Genghis and his descendants the Mongols did not use siege weaponry, nor, as far as I am aware, mass conscripts from defeated people in battle (mostly as fodder). I would say these qualify as increases in brutality. here is even an instance (apparently) where conscripted enemies were marched en masse into the moat surrounding the next city so that the city could be accessed.

An element of caution is advised with any source that expounds the degree of brutality of the Mongols, especially if they were written by their enemies and/or subservient peoples who had every reason to exaggerate their actions.

Define 'more brutal'?