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
http://mtgadventures.blogspot.com/2015/07/origins-set-review-plainswalkers.html
2. Angels and Thopters
http://mtgadventures.blogspot.com/2015/07/origins-set-review-angels-and-thopters.html
3. Elves and the Multicolored Cycle
http://mtgadventures.blogspot.com/2015/07/origins-set-review-elves-and.html
4. Spell Mastery
http://mtgadventures.blogspot.com/2015/07/origins-set-review-spell-mastery.html
5. Other Rares and Mythics (White and Blue)
http://mtgadventures.blogspot.com/2015/07/origins-set-review-other-rares-and.html
6. Other Rares and Mythics (Black and Red)
http://mtgadventures.blogspot.com/2015/07/origins-set-review-other-rares-and_4.html
7. Other Rares and Mythics (Green and Artifacts)
http://mtgadventures.blogspot.com/2015/07/origins-set-review-other-rares-and_38.html
8. Additional Commons and Uncommons
http://mtgadventures.blogspot.com/2015/07/origins-set-review-additional-commons.html