It.. works well enough. I really have no complaints, tho it does have some cookies, which I could do without (I don’t care to track how many trees I’ve contributed to planting, and I’d like a no tracking option) but that’s a pretty small complaint when I clear cookies frequently anyway. If you use ghostery or some other extension that auto-rejects cookies and randomizes data for those it can’t reject, you’ll be fine.
The sponsored listings are clearly labeled, the results typically come up fine. There do seem to be more sponsored results than there used to be, though, so.. something to be aware of.
It’s not perfect but it’s a lot better than google, and they use the money for trees (I did look into that claim and it’s true as far as I can tell)