I would not agree that The Prince is satire. What it is, in a sense, is a resume'. Machiavelli was trying to impress a new Italian ruler in hopes of redeeming his name and perhaps attaining a new station or position in government.
The Prince is a polemic attempting to explain the need of a leader to take an amoral but practical approach to political power. He was not necessarily immoral, yet he when he professed a need for morality it was for practical reasons rather than moral; for example he strictly admonished leaders from messing around with the wives of other noblemen and citizens as it offended them so deeply they might exact revenge.
Many of the themes found in The Prince are mirrored or echoed in Machiavelli's more significant work, Discorsi Sopra il Primo Decca di Livi, known better as Discourses on Livy. This longer work better fleshed out his philosophy in the disguise of a critigue of the old Roman historian, Titus Livius.
He did write humor/satire and this can be evidenced in Mandragola which evinced a rather raunchy side not totally dissimaler to Chaucer's "Wife of Bath" tale in The Canterbury Tales.
His writing certainly portray a man more concerned with the bitter realities of human existance rather than the sugar-coated desires that some dreamers would have us attend to, as was suggested in roo_ster's post.
