Do you still needed to scrub messy bits? Is it quicker than spraying with water, spraying with cleaning detergent, scrubbing messy bits and rinsing, drying?
On some spots where you couldn't see plastic a tiny bit of rubbing yes. But still quicker than using the traditional bucket method, although if your motorcycle was really dirty after offroading I don't think this method is good. The microfibre got so dirty after cleaning all that mud I had to throw it in the bin...
For 4 quid you can't go wrong, try it see if it'll work for your bike and how dirty you get it. I'm lazy and prefer this way, it would probably help if I rinse the bike first from the mud build up. But I seriously couldn't be bothered to go down to shell for a jet wash.