In a Washington Post review of the recently-released summer blockbuster "Pacific Rim," critic Ann Hornaday used the word risibly, writing: 

“Pacific Rim” is a big, lumbering, rock ’em, sock ’em mash-up of metallic heft and hyperbole, a noisy, overproduced disaster flick that sucks its characters and the audience down a vortex of garish visual effects and risibly cartoonish action.
And you know what? It’s not bad!

In the most general sense, risible means "laughable." But a quick scan of the usage examples on risible's Dictionary page will fine tune our understanding of the word. 

First, the usage examples show us that risible refers to the kind of laughter you reserve for the ridiculous.

The aesthetic, in other words, risks being risible.
– The New York Times (Apr 6, 2012)

Next, we see that risible can be fun. It's perhaps a cousin to Schadenfreude, though it refers to the excesses, rather than the misfortunes, of others. 

At one time, gentrification at least provided us plenty of risible but creative development names. now, not so much.
Time (tweet) (Feb 10, 2013)

And finally, we come full circle to risible as the perfect word for a piece of art you laugh at rather than with.

But the performances and script are baffling, verging on the risible.
– The Guardian (Jan 13, 2011)

So now we know exactly what Hornaday's verbal joy ride of an opening line means. "Pacific Rim" might give us the chance to have a chuckle at an over-the-top spectacle of fight scenes and future tech in a deliciously fun, slightly smug, but mostly mirthful way. A rite of summer as much as heat waves and ice cream.