I buy plenty of content from Amazon (video, kindle, audible) but I'm increasingly reluctant to use Amazon for physical products - I rarely buy paper books and when I do its usually from an actual bookshop (maybe 4 physical books last year compared to about 30 from audible and maybe 20 on kindle). I certainly wouldn't use them for anything over £50 or so - I'd go straight to a dedicated retailer that I have more confidence in.
I have great success getting second hand books through amazon. My wish list is up on camelcamelcamel and then every so often someone comes along and puts up a book I want for dirt cheap. I get a notification and if I am quick enough get the book ordered straight away. I've managed to get some books that normally go for £40 for £5 + postage before.
I used to use Amazon for second hand books, and then I noticed some sellers were not accurate in their description ("like new" had food stuck in the pages). Amazon was great at refunds, but I'd prefer to avoid the need to refund things. I noticed I was buying all my books from Wordery via Amazon, so I just went direct to Wordery.