I don’t use them much, although we don’t go a day in work without one of their boxes arriving, one of the subbies loves them.
I kind of assume they’re the online retailer for people who’ve never used any other online retailer.
I do all the purchasing in work, but I really don’t like them. Their site is a mess, they don’t sell a lot of stuff I need, which you think they would. The whole prime / business / 3rd party seller via Amazon thing is a hassle I can live without, their sales practices are a joke “This is £150 with Free Delivery” buy “This is £150 with Free Delivery in 4 weeks, or £20 tomorrow”.
Oh and despite all their optimization of humans, tax dodging and massive buying power, they’re NEVER the cheapest.
I will admit they’re good for one thing, Xmas shopping, get a list from the Mrs, buy the lot with one of their 1 month free Prime things, have the lot sent to work, get over the fact I could save money buying else later on.