I had a chance to finish the last part of this one earlier in the week and enjoyed it very much. I tested two of the new creatures in Oath, Azor and Zacama. I complemented Zacama with the Auriok Salvagers set up since he's quite the impressive infinite mana-sink. I also read recently that someone played Zacama in a local event and had some success.
Overall though, I would say he is win-more. He is able to seal the deal in positions where just about any other large creature would be able to do the same, but with few distinct strengths over the others and several weak spots, although when he does win big, it is fun and sensational. We don't always have the luxury of abundant developed board states that can activate him effectively, he's soft to Jace, can be overrun with creature armadas, and there's no way of determining the correct course of action with Oath of Druids on the stack. What I mean by that is that against Workshops, in certain situations for instance involving Tangle Wire, during my upkeep I would have to make a decision about whether to fetch a land, whether that should be a Tropical or Tundra, and then decide if, given limited resources, I should anticipate Auriok Salvagers appearing and produce white mana or Ancient Grudge going into the yard and produce green mana. Orchards and potential future life loss complicate the equation. With Zacama, you have no idea whether he'll actually appear and you can't predict whether you should tap the lands prior to Oathing and if so, which color(s) they should produce. If you don't tap one or two lands if that is all the mana available mana, you might not even be able to activate him once that turn cycle, which is abysmal.
The best thing he did for me was to destroy a Stony Silence before he got Plowshared; at that point I may as well have just Oathed up a Reclamation Sage. I used him once to destroy a Rest in Peace, but the Salvagers plan was superfluous at that point so it was again, win-more.
He was fun to have in play and scored style points, but Inferno Titan outclasses him in nearly every way. Even when I hardcast him on a very developed board and destroyed a Containment Priest and non-disruptive Thorn of Amethyst, it accomplished nothing substantial beyond what an Inferno Titan would do for 66% the price.
Azor on the other hand is surprisingly functional in combo metagames. There are several things that could have been done in design to make him stronger (these sets do have the whiff of "let's scale the power down") but his ability has kept me alive v. Combo decks during that critical post-Oath turn where few creatures other than the obscenely uncastable Griselbrand would. He wants a Tolarian Academy supporting build in order to use the Sphinx Rev ability but even without that he was not horrible. It bears noting that his Silence effect can be reactivated with a Jace bounce + replay, which is sometimes the correct move.