Tried it this afternoon.
Customer heard popping noises behind the soil stack cover and the socket ring fuse had blown.
After investigating under the bath to no avail I drilled a 50mm access hole downstairs - and with the camera was able to see where a leak from the bathroom had run down and saturated a taped up choc block - cables burnt out. Typical bodge job.
Luckily cables were long enough to be fished out of the hole, made good with maintenance free connections, secured in a connector box with tie wraps holding cable, taped for good measure and poked back in place - bit lucky to find it that easily. All tested fine.
The camera gives a good picture and illumination is fine - but in a featureless cavity it's hard to know what you're looking at as there is no sense of scale or orientation - probably needs a bit of practice. There is no zoom in or out function on the camera - don't know if more expensive models have this facility.
Also unless in a closely confines space it's difficult to control the gooseneck over any distance. I doubt if I'll ever use more than the first 9 inches - which is probably good advice all around!
Overall a useful piece of kit!