After a year of use I dont think Honey helped me save more than 10€. Websites I visited often didn't work with Honey, or I could fine better code in 5 min. Codes from youtubers and others are nearly always better.

Also, Honey collects a lot of data, even without an account. For every visit of a page in an online shop, Honey logs at least the following information: a timestamp, multiple unique IDs for user, session and device, the operation system, the browser and browser version, geolocation details, and the full URL of the visited page.
They also log infos on other websites like forums or support pages.

The idea is great, the execution really isn't.