my wife had a kindle keyboard, but since we upgraded to the new iPad we sold that bc she didn't use it all that much. Only downside I see though, if you use Amazon Prime and want to read free books you can't do that on the iPad app...you MUST own a kindle. Now if you read books daily...you may want to keep a kindle around. We just didn't use the kindle that much to justify having both devices around since we like to keep things simple.
Not true at all... I "bought" 3 free books tonight. I did have to go into my amazon account and send them to my iPad. But it wasn't a problem. I'll have to do the same thing if I want them on my iPhone.