Hm. I clicked on "latest stable release" and there I was. "To upgrade from an older version of Debian...".

I'm not sure how to re-structure the front page to improve this.

It didn't occur to me to click on "latest stable release"; in fact I hadn't noticed it was even a hyperlink. I generally look for hyperlinks containing verbs, or words like "instructions", or things related to what I want to do, not random nouns that have something to do with what I'm about. Therefore my eyes were initially drawn to the next short paragraph: "If you'd like to start using Debian, you can easily obtain a copy, and then follow the installation instructions to install it." I read that bit, and decided it didn't relate to me because it was all about installing from scratch. If there'd been a bit next to that saying "Alternatively, if you're upgrading from an earlier release, do read the release notes or things might go horribly painfully wrong", I'd have noticed immediately.