With their well specced new tablets, Amazon has unveiled the best alternative to the iPad yet. It is significantly cheaper, with up to $500 savings for the 4G variant with the base plan, but it really looks like a content consumption device, with a significantly worse software offering. Amazon has not even revealed in fine print the base OS, nor can it display ePub natively. So it will maybe cause Apple to slightly cheapen the iPad ( likely by doubling memory at the same price points), but a $249 iPad mini should be safe.
Also Amazon is saving money by reducing the size of its offerings compared to the iPad. As seen in the table, Apple's offerings are a good deal bigger, mainly thanks to their 4:3 ratio which helps a lot when having to edit something.