I guess the UK is such a compact market that most ecommerce plays are easier compared with larger markets so Amazon's "USP" is simplicity rather than uniqueness. I could get a decent number of products from Argos the same day, my food (/homewares) delivered in a 2 hour window the next day from any number of suppliers (and if rumours are true that the aforementioned Argos might merge with a supermarket, challenger right there).

Their main benefit is in selection, price (that isn't quite as dominant in some things as it was - although it's potentially going to destroy their competitors before they themselves match Amazon) and having a slick checkout process with all of my info in there.

Obviously this is why they're focusing on own-brand, specialised products and selling infra, but then do we see a day where Amazon has its fingers in so many pies in such a big way that they have to be broken up?