This has recently been exposed to be a big scam. Steals comission money of content creators and only gives you a coupon the store (that partners with Honey) tells Honey to give you. (Let's say Honey gives 5% discount at checkout, but there's a 20% coupon code you can find on the internet that actually works. The store tells Honey 'Hey, give them the 5% coupon code and don't show them the 20% one. We win, the customer loses'). Their whole 'Honey will always give you the best price and if not you can rest easy you got the best price already!' pitch is a complete and utter lie.

Look up "Megalag" on Youtube. He spent a long time investigating in detail with a second part coming soon.