It seems like he abolished serfdom in Poland and introduced a sort of mixing between Germans and Polish.
Frederich the Great managed to transform a small and insignificant state into one of the five European great powers that would shape the face of the continent until 1918. Unquestionably he had a great strategic talent. He was able to see the weak spots at his neighbors and he was ruthless enough to use those against them, otherwise he wouldn't have been able to steal Silesia from the Austrians and to forge an alliance against the Polish-Lithuanian Commonwealth and in the aftermath shoot an old European big player out of the game and erase it from the map.
He was probably gay! As a young man, he wanted to desert from Prussia with his putative lover an Hans Hermann von Katte in order to escape his tyrannic father Friedrich Wilhelm I. - the so-called "Soldier King" - who only cared for military matters. They were caught and incarcerated at Küstrin (present day Kostrzyn nad Odrą) . Frederic II. then was forced to watch the public decapitation of his friend Katte. He was so shocked that he lost his mind and fainted. After that he was still incarcerated for weeks and treated like an ordinary prisoner. It took the Roman-German emperor Karl VI. in Vienna, who interfered in this matter and expressed his concern to the "soldier king" that this is not a way to treat a person of noble blood that once would inherit the Electoral throne of Brandenburg. After these traumatic incidents Frederic II. personality changed and he hardened.
He was a great admirer of literature, his friendship with Voltaire is well documented and he even wrote music. The "Hohenfriedberger Marsch" is a great piece of march music. But he also was an emotionally cold man, hated women, rarely had a good word for his servants and did not spare the lives of his soldiers that he wasted in many battles.
So is he a model for the 21. century? Surely not! He probably made Prussia great but he also made the Prussians small. When he died Prussia was a great barrack yard. It is sad that other states had an army but Prussia was an army that had a state. His influence on Poland was surely devastating for Poles and what is with Germany? A weaker Prussia would have been even better for the Germans because Prussia then may have been merged into Germany and not Germany into Prussia, as it was in 1871.