Their recommendation engine is good, but only for individual products. It also gets screwed up if you buy something in a profitable niche outside of your typical profile -- I bought a book once about a gay latino's life for a class and received lgbt and latino recommendations for years that were not very relevant to me.
A pretty basic use case for people who read serial novels (ie. millions of people) is the ability to recommend a series or books within a series. People can down-vote me because Amazon is a cool company, but it's a use case that they just don't fulfill.
"recommendations for years that were not very relevant to me."
You can go into recommendations and there's a drop down where you can tag why a recommendation is inappropriate, tell amazon it was a gift and the whole topic will magically, nearly instantly, disappear.
I had the same issue with Thomas the Tank Engine and I'm not sure which of us had it worse.
Its a UI failure in the checkout process, just because I don't want amazon to wrap my gifts for me doesn't mean that I'm buying something thats not a gift at checkout time.
Its also a backend failure, come on Amazon lets think this one thru a bit, looking at the rest of my ordering history do you Really think I'm a big Thomas fan? Really? I mean he's cool, sure, but...
A pretty basic use case for people who read serial novels (ie. millions of people) is the ability to recommend a series or books within a series. People can down-vote me because Amazon is a cool company, but it's a use case that they just don't fulfill.