Interesting! The UK site http://www.amazon.co.uk/ has a similar front and centre promo for the Kindle Fire, but without the comparison to / attack on the iPad Mini.
If I recall correctly, you can't call out a competitor by name in UK advertisements. All the tv ads we have here will say "compared to the next leading brand..."
Unless that's changed recently. I moved away 4 years ago.
I believe it was changed in the last few years, but it's still pretty uncommon. The only examples I can think of, off the top of my head, are by the supermarkets (particularly those from Asda).
Thanks, it makes sense that Asda would be one of the first to take advantage of a change in law, I recall Walmart bought them out a few years ago.