Italy's 18th-century woman-slayer is portrayed by Ledger as a good-natured hottie who can't help but avail himself of the pleasures of the female flesh. Sienna Miller plays Francesca Bruni, a bookish firecracker who strains against the limitations imposed on women of her day and promotes the work of a feminist philosopher. Of course, once Casanova gets sight of the single woman who won't have him, he's smitten, politics be damned.
The role may come naturally to Miller, who has already fallen in love with a charming blond whose mere glance inspires women to remove their clothing -- in Alfie and in real life. Now she's back at it, and we imagine that even the Venetian extras strained to withhold their Jude Law jokes. One wonders whether her performance, one of the least interesting in the film, was not tainted by experience; then again, the problem could be the role itself, as the writing is less than inspired.
Anyway, the plot. To avoid prosecution as a libertine, Casanova must marry within three days. (Yeah, just go with it.) He finds a willing virgin and becomes engaged, but in the process, ends up in a duel with a competitor for her hand. His opponent, agile with a sword, is unmasked as a woman -- the same one he witnessed a few days earlier, making an impassioned speech for female rights. It is, of course, Francesca Bruni, standing in to save the hide of her nonathletic brother. In the parlance of this familiar narrative, Casanova has met his match, and the chase is on.
The obstacles: Casanova is engaged, and so is Bruni, it turns out, in an arrangement finagled by her departed father to rescue the family from debt. Also, she doesn't like Casanova. Even before she learns his true identity (he pretends to be quite a few other people), Bruni isn't swayed by Casanova's protestations of attraction, which are based -- as they always are -- on little more than lust. She's the kind of woman who requires a man to earn her love.
None of this is particularly interesting. What makes the film fun is everything else -- namely, a series of enjoyably convoluted twists and turns that introduce and employ hilarious characters. Jeremy Irons is delicious as a priggish and bumbling bishop, swathed in "papal purple" and wearing a wig that marries the mullet to a row of hedges. Oliver Platt is even better as Bruni's fiancé Papprizzio, a lard merchant from Genoa who arrives in Venice on a barge of fat. Pratt plays Papprizzio as huge, adorable, and sympathetic, desperate to be liked by Bruni, whom he has never met. Screenwriters Jeffrey Hatcher and Kimberly Simi were smart to make Papprizzio such a love; if he had been a boor, uninterested in Bruni's opinion of him, it wouldn't have been half so funny.
In fact, director Lasse Hallström (The Shipping News, Chocolat) gets away with pretty much everything by employing a brand of simplistic feminism that nobody can object to. That's the only way to make a sexpot protagonist palatable to viewers of period pieces (in a word: women), and it basically works. As in many romantic comedies, the love between the two principals isn't given much time to develop, and it's never entirely believable. But the script is so busy contriving farcical scenes of mistaken identity, slapstick, and general buffoonery that it hardly matters. One minute we're at a ball where pigs are being led on leashes, Casanova's two fiancées are competing (unknowingly) for his time, and the parents of both are scheming to bring their children into line; then we're in a hot-air balloon, sailing over Venice against a backdrop that's obviously been fabricated. The point isn't to learn, but to laugh.
The last 20 minutes of Casanova are ridiculous, with a succession of genre conventions that don't mean much, but it nevertheless maintains its sense of humor. It's hard to fault a movie that seems to be having such a good time, especially when it springs from a deft script. You're likely to leave the theater in the mood to hum.