The pdf is 58 pages (counting covers and OGL) and is gorgeous. I love the borders and page layout. The artwork is fitting. Some is modern, but there's a lot of classic public domain artwork and in the context of this book it's appropriate and looks phenomenal.
To keep with the simplistic approach of the title, most of the book discusses how to using existing Player's Handbook content in the setting. This doesn't mean there isn't new content. There's quite a bit actually.
Three new races emerge from the primordial stew: nature loving apefolk (with orange fur, strong back, and long limb subraces), slow adapting and nomadic Neanderthals, and ancient noble saurian (with big teeth, big stomper, and tough skin subraces).
After discussing how the classic classes fit (or don't in the case of monks and wizards) in the setting, we're presented with new archetypes. The Bard College of Primal Rhythm is combat oriented. Clerics can take the Oracular Domain to draw from nature and see signs for divination. Since the monk isn't appropriate, the fighter gains The Fist is a primal brawler and force of nature. Finally Warlock's of the savage lands sometimes make deals with personifications of primal nature. Thus we are given the Volcano Warlock Patron.
The Arcana and History skills aren't appropriate in this setting. They are replaced with the Intelligence based Lore skill. In addition, there's a background for being raised by wolves, apes, and other animals. It's known as the Abandoned.
Since industry and such doesn't exist, there's a large section of new equipment, including vehicles and pre-historic trinkets. There are new magic items, such as daggers created from meteor shards and healing fruit (which are more potent than healing potions, but take longer to be consumed).
One of the most important sections (in my opinion) discusses actually using this in your game (with pros and cons). Are the savage lands a new continent that's not been settled? Or is it a hollow earth style scenario? Perhaps there's a primal plane of existence. After discussing the where, the pdf goes into the what. This section is a primer to the cultural aspects of this setting (including a side bar for the gods of the savage lands).
There are a few new optional rules. Detailed foraging and hunting rules (with DC's are presented).
Finally there's a bestiary section. A lot of space is given to discuss how to use traditional Monster Manual (SRD) monsters in the setting. However, there are a few new beasts and foes presented. My favourite is the powerful chaotic fey, known as the Mountain Queen. She used elementals, monsters, and other creatures to impose her will. In addition there are new dinos, such as the headbutting pachycephalosarus, the fearsome looking therizinosaurus, and the undead skeletal pterodactyl. Finally, killer plants are a staple of lost world stories, we're presented with the vine abductor. This malevolent plant can pull an Invasion of the Body Snatchers and sprout clones.
I'm glad I picked up this pdf. While I don't know that I would run a full pre-historic game, this would be an excellent resource to do a Hollow World style game. I think this is 6.95 well spent. I'm really looking forward to seeing what the future holds for this series.
Honestly the setting reminds me of Far Cry Primal and that alone makes me want to play it.