A DECENTRALIZED FINANCIAL SYSTEM
Zen is a parallel blockchain to Bitcoin. The team is focused more on the technology at this stage. Multihashing, UTXO, Light Security Clients are competitive technological features.
"Parallel blockchain" is an alternative approach to smart contracts. So already in this sense, Zen is a derivative of Bitcoin. If Bitcoin is "the winner takes all" payment system and token, then Zen might benefit greatly. Probably, the same technology can be rebuilt for another emerging "winner takes all". Moreover, Zen can strengthen the case of Bitcoin if Zen is successful in the real applications. Can Zen block bitcoins and therefore be able to exploit multiple application of collateral? No, as far as I can see. Is Zen more efficient as some kind of "off-chain solution" rather than Lightning Network, Sharding, etc. - a technology and scalability question?
Zen targets financial use cases. 0x is a competitor. Merklized Oracle is a main challenge. It would be interesting to use existing conventions for conventional derivatives without relying on oracles? The fees payable to oracles will mean that oracles are effectively intermmediaries, not necessarily self-regulating. The economics of oracles must be considered anyway. The integration between open-crypto and conventional finance system might be a promising direction.
Zen applications require building markets for small and medium actors, and this is the question of economics and product-market fit, not a blockchain question.