'Serious Photography with Instant Film' sounds like an oxymoron to me. Back when I worked on instant photographic systems we used to say that 'an excellent instant photo is one you wished you had taken on real film'.
All I can say is that the Instax film my kids shoot with is VERY Impressive. Sharp as a tack, with gorgeous colors. I just wish the images were a bit larger and that Fuji made a monochrome pack to go with the camera.