Extreme ultra-wide lenses are never perfect. Keeping this in mind the Laowa is pretty good indeed. It’s super-sharp in the image center and if you avoid f/2.8, the borders/corners are decent. Lateral CAs are generally not an issue. Image distortions are extremely low for a lens of this focal length – and that’s without image auto-correction. The primary weakness is vignetting which is rather extreme at max aperture. However, at medium aperture settings, it’s a lesser issue outside of lab conditions. Flare in strong contra-light can produce quite a bit of glare – a generally weaker aspect in Laowa lenses it seems.
The Laowa 9mm f/2.8 Zero-D may have some shortcomings but that being said we really enjoyed using the lens out there. In real life, the fully manual character wasn’t really an issue. Given the depth-of-field of a 9mm lens you can pretty much guess the focus distance and if needed for close-ups, you can just use magnified focus view in your camera. For most of us, a 9mm lens is quite exotic already thus it shouldn’t be a burden when carrying it. The form and size factor is pretty perfect if these are your constraints as well. We heard that the Laowa 7.5mm f/2 MFT is pretty popular among the drone folks. The 9mm f/2.8 Zero-D has the potential to do the job (and more) on APS-C mirrorless cameras.