Conversation so far:
What is the Evaluation of Frederick II?
Historians rate Frederick II as a highly significant European monarch of the Middle Ages.
What is one noteworthy accomplishment that Frederick II did while Holy Roman Emperor?
His Sicilian royal court in Palermo, beginning around 1220, saw the first use of a literary form of an Italo-Romance language, Sicilian.
What else did Frederick II achieve?
Frederick II was also the first king to formally outlaw trial by ordeal, which had come to be viewed as superstitious.
Were there any attempts to overthrow Frederick as Emperor?
Frequently at war with the papacy, which was hemmed in between Frederick's lands in northern Italy and his Kingdom of Sicily to the south, he was excommunicated four times
How did Frederick II achieve continuity as Holy Roman Emperor?
The modern approach to Frederick II tends to be focused on the continuity between Frederick and his predecessors as Kings of Sicily and Holy Roman Emperors.

Question: What are some negatives or failures of Frederick's reign?
Self-contained rewrite: What are some negatives or failures of Frederick II's reign?