if you want to use the camera preview with VNC remote desktop you have to enable direct capture in the Troubleshooting Menu of VNC Server.
if you want to use VNC remote desktop to a Raspberry Pi with no HDMI monitor connected you have to use raspi-config to set a specific desktop resolution using the Resolution Option in the Advanced settings.
You can adjust the lens distance using a tiny spanner, but I’ve not done this. So it might be possible to get even sharper pictures.
The picture quality of the high quality camera is very good. But then again you’ll be paying around 100 pounds for the sensor-lens combination and so you’d expect something pretty impressive. I’m not sure how much the sensors in mid-range compact cameras cost, but I’d expect them to be around the same quality.
The “telephoto” lens that I got has quite a narrow angle of view, so if you want to do general stuff I’d suggest getting the wide angle lens instead.
Things will get properly interesting when these devices get into the hands of all the smart people that like to play with Raspberry Pi. There is considerable scope for some very interesting devices and if you want programmatic access to a very high quality image you’ve got that now.