How well does it actually work to surgically reroute the optical nerve?
At least two follow-up studies have investigated the behavioral consequences of the re-routing of the optic nerve to the auditory cortex. In these animals the visual cortices were ablated, and the optic nerve re-routed by combined lesions of the superior colliculus and ascending auditory pathways to the thalamus. These lesions induce retinal axons to form permanent ectopic (i.e., re-routed) projections to the auditory thalamus and cortex. These ectopic visual projections result in the formation of retinotopic maps in the auditory cortex and in visually responsive neurons with receptive field properties reminiscent of cells in the visual cortex.

These re-wired ferrets and hamsters were shown to have functional vision, as shown by their ability to tell light from dark and to recognize simple visual patterns. Visual pattern recognition was absent in control animals that were blinded, but not re-wired. Visual function, as measured by grating visual acuity in re-wired hamsters and rats, was however not as good as in control animals with normal vision (Frost et al., 2000; Melchner et al., 2000). 

References
- Frost et al., PNAS (2000); 97(20): 11068–73
- Melchner et al., Nature (2000); 404: 971-6