Seems like an advertisement for a book to get access to the content. The book is authored by the same person who wrote the article and the poster is new. I flagged it
It is, but the website itself contains no explanation of what it is. Yes your submission has a short, descriptive title, which is good, but the site is still very confusing to land on as a first-time visitor. Especially with the table of contents that goes nowhere.
Couple that with the fact that the website is mostly made up of ad banners for 3 separate products, it makes quite an odd Show HN submission (unless the Show HN is actually "Show HN: I wrote a book called Data is Beautiful", in which case I'd suggest updating the title.