In summary, I really like this set. It is a great pairing with M15. Both sets have great artifact support, which has been somewhat lacking in Tarkir Block, Theros Block, Return to Ravnica Block, and Innistrad Block. A third core set that could be made a three set cube with M15 and Origins is M12.
Here are links to all of the Origins Set Review posts.
1. The Plainswalkers
2. Angels and Thopters
3. Elves and the Multicolored Cycle
4. Spell Mastery
5. Other Rares and Mythics (White and Blue)
6. Other Rares and Mythics (Black and Red)
7. Other Rares and Mythics (Green and Artifacts)
8. Additional Commons and Uncommons