As the article says, this affects only shadow quality. And if you look at the video, the shadows are indeed improved. Still:
it's not such a huge visual difference
they're only using a single light source
there's some kind of optimization, with it only being supported on undamaged tanks.
So, it's extremely limited, though certainly impressive. I would like to at least see ray-traced reflections. Also, for a battle game, you really want muzzle flashes and explosions to provide illumination - especially at night.
BTW, definitely check out the "Developer Diaries" video, at the bottom of the article. That was very well-made. Somebody put a lot of effort into that.