I tried this over a year ago and was disappointed: the better prices on Amazon were few and often referred to products not exactly the same.
I just tried it again and went through my extensive wish lists and got the same results. A few cases it found one better result on Amazon, but Amazon already had that listed under "Other sellers" - in one case, Amazon's "Other Sellers" list had one better price than Honey found.
I'll keep trying it for a while, but expect it to be a waste of time.