In short:
- Nice and small (but you knew that)
- Sharp wide open in the centre, but soft in the corners at all apertures. Due to huge amount of software stretching of the origjnal distorted images
- Little coma (surprise)
- Very little flare
- Lots of focus breathing for video
The poor image quality in the corners would tend to reduce its value as an astro lens. What wasn't clear was how much cropping is needed to get to good resolution. I'll stick top my Samyang 14/2.8 as my astro lens.