That study doesn't say anything as to whether high-fructose corn syrup is unhealthier than regular syrup. That study's only claim is that mice gain more weight if they eat high-fructose corn syrup compared to normal syrup. I think they could have probably counted the calories within each sample and saved everyone a lot of time.

And who's to say additional weight gain is bad for those mice? Mammals in a cold climate might appreciate the additional weight gain.