Having never played any of the flavors of Runequest, ever, it's hard for me to critique this core rulebook's rules (though I am a fan of the parent ruleset and was intrigued at the 1st set of Mongoose Runequest ruleset -- but that's another story). However, as a sourcebook and a spark of inspiration I can offer my opinions.
First off, the setting is one that I thought I was familiar with -- a swashbuckling setting with clockwork marvels -- but I was quickly proven wrong. The game is anchored in the time of the struggle of King Charles I and the English Parliament, with all the political and religious turmoil of that explosive era. Mix in alchemy, clockwork machines, and a changing view of the world, and you have an RPG already very different from the archetypal smooth talk and swordplay model of gameplay.
There rules for character creation seem pretty straightforward, with the 30+ professions and descriptions giving a great feel for the era. The Factions section (and their interrelated nature with the Righteousness mechanic) adds both flavor and potential richness to roleplay and gameplay possibilities.
The illustrated sections on Weapons and Armor will lend players and GMs alike passable expertise on the era's implements of war, and the sections on Alchemy and Witchcraft put a different spin on the traditional view of spellweaving in RPGs, while the section on clockwork devices help frame and make playable this particular conceit of the game. And the source material doesn't end there: maps of Britain, Scotland, Ireland, Europe and the New World; Wages and the Cost of Living, History, Important People, etc.
And there are sections on gamemastering this RPG, a couple of adventures to get you started, and a useful index to find all sorts of material in this dense, seemingly complete RPG corebook.
There are some problems with the PDF bookmarking of the my copy, but these can be easily rectified I'm sure in future iterations of the PDF.
All in all, a fine addition to my RPG collection.
[5 of 5 Stars!]