I use this on my basses and guitars, and it works great! cleans and shines up, pleasant smell, too. I use a generous amount on the front, back or neck, leave it on for 10 minutes or so, and then use a fiber cloth to work it in and remove excess.
I don't think it does anything for protection though- it can buff out some scratches and hide some dents, but it doesn't really prevent them from happening.
I bought a used bubinga bass from 98 some time ago that i shined up with the wax, and it made a world of difference, so if your wood finish instrument looks lackluster, definitely give this wax a go!