This is a lightly-revised and reformatted version of the Free FATE rules by R Grant Erswell, which have been floating around for a few years — you can get the core at http://www.ukroleplayers.com/downloads/free-fate/ and the magic system supplement at http://www.ukroleplayers.com/downloads/free-fate-magic/-
The layout is improved over the originals (which were just vanilla Word documents with minimal formatting.) It's still pretty minimalist, but more readable and attractive, and they've added a TOC, index and character sheet. There's no artwork, but it's not really missed since this is a pure ruleset with no setting.
I haven't had a chance to compare the content, but for the most part it looks identical to the two original documents mixed together. Free FATE itself is a nice stripped-down version of the rules from Spirit Of The Century, sort of a reverse-engineered SRD of it. As such, it's well suited to pulp style games, as depicted in the running examples throughout the book. The magic system makes it more feasible to run fantasy, although it's probably still best suited to urban fantasy since there is no built-in support for the tropes of heroic fantasy or sword-and-sorcery (fantasy races, medieval weaponry, monsters, etc.) Of course there's nothing stopping you from making up your own.
At its current (introductory?) price-point of $0.00 this is a nice product, and I think Vagrant have done a good job of polishing the original work. I do have serious issues with the list price of $9.99 — that's a heck of a lot to charge for a digital-only book with minimal layout and no artwork, where they didn't even write the text themselves. Its starting to smell like exploitation, unless they're planning to give Mr. Erswell a fraction of the proceeds.
Personally, my recommendation is that this is a no-brainer as a free download, but when they raise the price you're better off downloading the original free document (see the links above) and making do with it until Evil Hat releases the long-promised FATE Core book in early 2013(?)
[3 of 5 Stars!]