No, not nearly as powerful as full booleans.
Essentially, all it does is keeping track of IORs: Currently, Cycles always assumes the ray comes from air or leaves into air (depending on surface orientation). With that patch, Cycles knows what IOR it is currently in and refracts accordingly.
An example where that is relevant is a glass with water: Currently, it’s rather tricky to get the glass-water-interface correctly. Add air bubbles or ice cubes, and it gets pretty much impossible to do it manually.
The boolean example I mentioned is just two spheres overlapping, where one has IOR=1 and one has IOR=1.5. The first one is invisible, but as soon as the ray hits the second one as well, you get refraction => What you see in the end is the difference of the 2 spheres.
Anyways, that’s just a neat side effect, not the indended usage.