I only know them from their Dutch branch Thuisbezorgd, which seems fairly decent, and has contracts with connected restaurants. Quite recently they've been under attack for abusing their near-monopoly (they do have Deliveroo and Uber Eats as competitors, as well many independent restaurants; many connected restaurants also have their own site) by raising their margins, putting pressure on restaurants.
GrubHub sounds like the worst of the worst, so I was quite surprised to learn they were bought by Thuisbezorgd's parent.