I've had another go with this in recent days and I'm happy to say that my initial frustrations were simply down to a passing case of noobitis ...
It's all in the angle, you know. I know ... I know ... slate a razor and then find it was you, all along, not getting the angle right when ... and here's the kick in crotch: the angle is pre-defined for you by the manufacturer. Like injectors, this razor is simply a case of putting the head up to your face and putting the flat bit on skin and drawing down. Done like that it works a treat.
Given this was the first (THE first) cartridge razor, it's quite a treat to shave with one.