Well, it was the only anamorphic I could afford.
Even the huge, heavy Lomo projection anamorphics are more expensive than this (the Sun was about $100). If I use my Helios-44M at F4 the image is actually pretty sharp and the vignetting is not very bad, but apparent, the sides can be cropped. If I use my Jupiter-9 it gives decent sharpness from F4 too. I did some close up test, 2 pictures, one without the Sun and one with the Sun and there was no major degradation in the focused areas. My only concern is setting proper focus.
Compared to other anamorphics the Sun might be worse but I don't know, it looks OK to me, I wanted the artistic effect of it, not pristine image quality. I'm still waiting for my friend to machine a clamp for holding the anamorphic lens properly. It will surely be easier to focus with the lens held tight.