The biggest selling point of the pen for me is, that while it works with special kinds of books, the books are not tied to any account.
You can get a book from the library, buy a used one or borrow one from a friend, it will work with your pen.
This is so refreshingly different from all those subscription models, that I keep buying the books and once my kids grew out of them I know I can gift them away.
Note that while it seems that you need an account to download the audio files, this isn't actually the case. It's just the stupid UI on their web site that makes it look like that. If you find your way through that UI, you can get the audio files without logging in, and the pen announces itself to the host computer as a thumb drive -- just copy the files into the root directory.
You can get a book from the library, buy a used one or borrow one from a friend, it will work with your pen.
This is so refreshingly different from all those subscription models, that I keep buying the books and once my kids grew out of them I know I can gift them away.