I have the S2 Pro and I was quite disappointed with the OS they enforced on it, which was a custom version of Android 7 that doesn't allow any custom launchers. This made the phone not as snappy as I would want for and ex-300$ phone, however I did assume the risk when preordering without knowing anything about it's OS.
Now here I am again ordering the S3 Pro for 258$ and hoping this company doesn't put this model to shame once more.At least now I know they will be shipping with Stock Android 9 so that fear's out of the way.
My only concern now is that the whole camera advertising might be very hyped-up and despite the capabilities of the hardware, they might do a very sloppy job at implementing the software, which could totally darken the experience for us users.
+ I think that missing Optical Image Stabilization will be a regrettably lacking feature for such a powerful camera-phone.