Yes, Kindle is thru Amazon only. I found the prices are comparable, and the books, magazines etc are pretty much the same. I do wish there were more games to download as I love games.
The one feature the Kindle doesn't offer (at least the one I got), is the SD card, but that wasn't important to me as the Kindle can store up to 1500 books on it's own. Amazon has backup of all my purchases so I can retrieve them should I accidently delete a book or something happens to my reader.