Hi,
I have both a K3 and and iPad. I don't find the devices to be mutually exclusive. The iPad is great for media, and has a decent web browser. It does a much better job with pdfs -- although you are reading from a computer screen.
The kindle, imho, does one thing really well: it lets you read texts for a long time without eyestrain. The kindle's browser is functional, but slow. It is good when you need to access the Internet in a pinch, but I couldn't see myself using it regularly.
I'm not sure I'd want iPad-like features in the kindle. I want to be able to focus on one thing -- reading -- and nothing else.
Of course, ymmv, and this is very imho
-y