The release notes states:
"Avoid placing radius-based lights very close to, or even over, shadow caster objects. The algorithm can fail to render a full shadow in this case."
The image above shows the distance my light source is away from the wall. I also have a light radius of zero (anything higher, even 1, causes worse results).
I'm happy to have this... but at the moment I can't use it for anything other than effects, such as the god rays as shown in the op. Is this as good as we can expect it to get? I was getting better looking results with paster, but it killed the frame rate. This doesn't give great results all the time, but the speed it runs at is beautiful.