This book is a sequel of sorts to the Dawn of the Artifacts adventure series, which ends in a vague note, promising that all of its loose ends will be wrapped up here. Given this is a full-sized book, I expected it to both deliver on this promise, and to offer adventures and plot hooks for new artifacts, and maybe even rules to use artifacts in play.
I regret to say I was disappointed. "Artifacts Unbound" vacillates between wanting to be a sequel to Dawn of the Artifacts, a companion to the "Artifact Rush" plot line in the Shadowrun Missions adventures, and an introduction to the whole "artifacts" arc. It succeeds somewhat on the later two goals, but not on the first, which is the one I was the most interested in.
The main problem I had with the adventures and plot hooks in Artifacts Unbound was that they focus solely on the same four artifacts your PCs spent four long adventures chasing and obtaining. It weaves a tale saying they "don't want to be together" for some reason, and uses that as an excuse to have them turn up all over the world again and again. And again. And again. Most of the pages in the book are dedicated to sending the players after the same old four artifacts several more times, which devalues the effort they went through during Dawn of the Artifacts.
A few of the adventures here are appropriate as sequels, since they involve chasing after the secret to unlocking the power of these "Dawn" artifacts, or entirely unrelated items of similar power. They're not the majority of the material, though.
In short, this book will be far more useful for groups who haven't played through Dawn of the Artifacts. There's enough information here on the four artifacts from that series, and enough adventures focused on chasing them around to provide context. Groups who have played through Dawn of the Artifacts might as well just skip to the very last fiction piece, which delivers the promised payoff, and then play the independent adventures after that.