An adaptation of James Thurber’s classic “The Secret Life of Walter Mitty” — thanks to its steady classroom presence and general winning charms, one of the best-known American short stories of all time — is a daunting-enough task. That the 1947 adaptation still warms the hearts of millions worldwide makes a new version that much more of a challenging enterprise. And that this newfangled take is being helmed by Ben Stiller, as divisive a movie star/auteur/scruple-free-box-office-cash-in-dude as we have working today — and that he’s starring and directing — might just go ahead and make this, for you, a terrible idea. (Oh, right: And The New Yorker did a big piece on the softly labored Mitty production, which doubled as a big ol’ invitation to go ahead and bring out the knives.) But anyway: Now we get the first teaser trailer for the flick and … oh … damn. Hmm. Wow. That’s … that’s pretty damn lovely.