These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Dude, Not Funny!: For some the black comedies like the Putting-the-devil-back-to-hell story.
Fair for Its Day: Treated women as much more willful and independent than its contemporaries, and Jews as generally greedy but not actually evil.
Genius Bonus: The work is subtitled Prencipe Galeotto (Prince Galehaut), the go-between of Lancelot and Guinevere, a reference to the many go-betweens in Decameron and also a reference made by Dante in Inferno V.
Boccaccio was actually a huge admirer of Dante and incorporates a number of references to Dante in the Decameron and elsewhere in his work; for instance, on the first day, the courtier-diplomat who serves as a hero of sorts for one of the stories is mentioned in the Comedy as being damned to Hell for being an unrepentant "sodomite" (whether this means "homosexual" or "pedophile/pederast" is unclear) despite being an otherwise honorable and upstanding gentleman.
Older Than They Think: Most of the stories come from sources way older than the book; Boccaccio just brought them to his time.