Thanks for the samples, Eldar! Looks like a wicked sharp lens...blows my mind. Even at 100% zoom, I can't say I've ever seen anything quite that sharp before. To show you a bit more, here is the same shot at f2.8. You can see the bokeh change. The lights in the background is a Christmas tree, so the lights are pure lights or combined light and reflection from a Christmas ball, like the two with a red shadow. There are also reflections from the glitter strings. I believe a shot with pure light sources in the background would have a more even bokeh. When I have more time I will do a bit more thorough testing.
The one thing that did stand out was the boke. It looks like it is slightly spherical, but there are clearly visible concentric rings in each boke blur circle. If you downscale everything, that becomes invisible, but if you wanted to print large, might be a problem.
It isn't the amount of boke I was referring to. I hope you don't mind me using your photo, but here is a 100% crop that demonstrates the strange concentric rings inside of each boke blur circle (are you saying that funky effect is because the light sources are christmas lights?):
That particular bokeh ball is a silver Christmas ball and it may be that you will get these kind of rings in that ball´s reflection. The strong lights are electric candles and they have a reflective edge, which makes an additional shadow in the bokeh. I posted one more with pure candles. That is probably more representative.
2x5DIII, 1DX, 8-15/4L, 24-70/2.8L II, 70-200/2.8L II, 70-300/4-5.6L, 200-400/4L 1.4x, Zeiss 15/2.8, 17/4L TS-E, Zeiss 21/2.8, 24/3.5L TS-E II, Sigma 35/1.4 Art, Sigma 50/1.4 Art, Zeiss Otus 55/1.4, 85/1.2L II, Zeiss 135/2, 600/4L II