And fixed, I'll let you see the problem of light leaking!

Even on the vase in Sponza light leaking causes some serious problems.

EDIT: By carefully setting parameters one can get rid of light leaking and achieve shadows for larger-scale area lights. See following screenshots:

The shadow is still noisy, which can be improved with:

• Better random samples/random number generator (mine is bad, I just put something fast together)
• More samples
• Temporal filtering

Although you can clearly see that the performance is hurting from quite large area light (yet shadowing it somewhat as expected).

By carefully adjusting parameters I got rid of light leaking to some extent (it seems a bit superior to PCSS in this sense), although comparing to PCSS the performance is lower, and it is still not possible to get rid of the performance dependency on area light size.

EDIT2: Actually they do look quite good with improving the noise function a bit. I also increased number of samples so that the shadow is actually smooth.

The main problem is still the performance - larger area light tends to kill it.

EDIT3: Decreasing samples in ray cast and for area sample points with better noise function and parameters gives almost acceptable results for lights.