This has been around for years, actually! You can sometimes get the premium seats on promo, and it would cost just a bit more than economy on a full-service airline. Tried it to ICN, and seat-wise, it's definitely better than seating in Y on any airline, and perhaps even better than some regional recliner J seats.

Of course, you get none of the perks and ambiance of a "real" business class flight. It's just a better, good-value seat if you want to catch some sleep on the plane.