No, DR Jeanne, I have never used any previous e-reader device.
bk, DR Ginny was correct, the primary difference between Kindle and other e-readers is the connectivity. Which kind of ties you to Amazon, for good and for ill. Amazon at the moment appears to have the largest selection of e-books [90,000 titles and growing daily - but that is only a small percentage of Amazon's stock], but it only accepts a few other formats besides its own proprietary format. Kindle books by and large cannot be viewed on other e-devices, and vice-versa. You can manipulate books from the
www.guttenberg.org project to work on Kindle. But for now, the vast majority of books on Amazon - including yours - are not converted to the proprietary format, nor are much of the print books already in your collection - which is certainly a limitation. You can, for a very nominal fee, have Amazon convert Word or .pdf docs to Kindle-ready "books." The .pdfs would be more successful if they are simple text and nothing complicated.
You do not get covers. There are no formats - it's just the text, so hardcover/softcover are indistinguishable - you're just getting the text of the book. No download charge at all - it's built in to the cost of the reader device and the Kindle version of the book. Most Kindle versions of the best-sellers are going for under $10.00. Things in the public domain [that have been converted and are available] can go from .99 to a few dollars.
It certainly doesn't replace a print book, and it has its limitations, but it is very convenient for reading on the go, and for books you'd like to read but don't really care if you own a hard copy.