Used to be superb... but recently Amazon.co.uk is nowhere near its past glory.
I've used Amazon.co.uk a lot in the past, primarily for books. Their catalog is simply amazing. However I'm not a big fan of their integration of Amazon market place, If I wanted to buy from a third party I'd go to their website. Furthermore it's rather hard to figure out which merchants on the marketplace that ship outside the UK and which don't.
Buying electric things from Amazon has also been something I have not been impressed by. Most things are sold with the plugs that are only used in the UK. This is fair enough as it is after all Amazon.co.uk. I just wish they'd specify which products are with UK plugs and which are with continental plugs, because the pictures often depict continental plugs while the product comes with UK plugs and the description rarely says it (I have a fair amount of converts so not as big an issue as it used to be).
Lastly over the last year I've noticed that the Super Saver delivery option has become the Super Slow delivery option. It only used to be the actual transit time that used to be slightly slower than paid postage. However now the dispatch phase has gone from 12-24 hours from order was placed to around 48 hours before orders are dispatch.
Its especially the deterioration of the Super Saver option that is causing me to place more and more of my orders with other sites when possible because without the postage price negates any saving and often raises the price to a level where order sites (and in some cases even store retailers) are cheaper than amazon.co.uk.