Still DRM-laden. Won't buy, even at 0 dollars, sorry. It's a question of principle: I'm strongly against DRM, therefore I will boycott DRM'ed products.
It offers downloading a windows app, no good for linux. It won't let me download unless i have a registered kindle program. Why can't they just let me download the file first? Significantly more friction than just downloading a pdf.
I have no (major) problem reading it online, but it just wont let me. If i go to your link, i am sent back to the kindle store. Then if i try to 'buy', i am required to have a kindle serial number, there is no other way to proceed. (I assume if gives you an ID or something if you download the app, but there is no 'read online without a kindle' choice).
It worked for me with my existing Amazon account, but then I have a Kindle.
I thought I'd test with a new account, so in an incognito window:
* Went to https://read.amazon.com/
* Created a new account
* Got redirected to Kindle store, found free book, hit "Buy now with 1-Click"
* Filled in a billing address
* Got a page thanking me for my order, hit "Read now in Kindle Cloud Reader"
* Book loaded
You're welcome to use this account--login: "M8R-2neeuu@mailinator.com", password "test123".
I agree that .azw/.mobi is an inferior format to .epub/.pdf, but Calibre is free software for Linux that converts most formats without an issue (and given that the Amazon version already has formatting issues, I doubt that's a problem).
The best thing to do, though, is what Cory Doctrow does: http://craphound.com/down/?page_id=1625. He even has (had) an option for a Gamebody Advance reader!