From the looks of it, pretty well. This is by and large the same Snapture you'd have found in Cydia or Installer last year: It lets you zoom and pan in liveview with multitouch, shoot three-shot bursts, snap a photo by tapping anywhere on the screen and file photos to a picture-in-picture tray in the corner of the screen, from which you can review, delete or save them. A reticle-like overlay helps you keep your hands level, while Snapzones let you prime shots so that releasing your finger—not tapping it—can trigger the shutter.
As far as I can tell, the only capabilities ceded to Cupertino are the real-time colour adjustments and camera timer, which were never the banner features anyway. Autofocus-by-touch seems to have been lost when using the app on the the 3GS, too, but auto-autofocus, for lack of a better phrase, still works fine. And hey, now that iPhone OS supports hardware accessories, and Snapture has traversed Apple's approval process, that promising flash attachment Snapture Labs had been working on seems like it might have a future.
Snapture now resides in the App Store, looking uncomfortable and feeling slightly out of place, for a limited-time introductory price of two dollars, after which it'll rocket back up to eight. It's not showing up in searches for the time being, but you can find it at this link for $2.49. [Snapture Labs]