Maybe for English-speaking countries. But iZettle is market leader in Europe and LatAm, so the counterargument could be that iZettle is more visually memorable and easier to pronounce than e.g. Square if you are not a fluent English speaker.
iZettle is huge in LatAm. Almost every small business I know that is starting to accept credit cards (taco stands, coffee shops, small stores) is using it.
Like WhatsApp, I imagine the company wasn't really on the radar for most people in the States.
I can't imagine using it - "Yes, I use my iZettle to process payments."