It is a working protocol that provides a much needed service to many various users on one of the most popular blockchain networks today. In my opinion, decentralised exchanges are likely to be disruptive to their centralised embodiment and gain popularity in the near future. Reck of that it has skin in the game with great working technology, it stands a good chance of becoming a popular choice for its services. However, as it is currently limited to exchanging ERC-20 tokens its future performance is intimately tied to a giant who has red hot competition on the horizon.
Technology: More than funds being held in a individual pool on the exchange that is vulnerable to attack, traders are required to hold their tokens in their own wallets. The Open Order Book is a decentralised order book that is maintained by node relayers. Relayers will keep the bulk of the transactions separate to the Ethereum network to avoid bottlenecking the blockchain.
Processes: Relayers are used in 0x that broadcasts the order they have to the 0x blockchain which functions like mini exchanges of sorts. Trade is done only if the user signs a counter order to complete the transaction.
The smart contracts that 0x is running are not specific to a single application. They are open sourced, their entity can use them to integrate them into their own application or service.
It is not like other coins, it is a protocol that essentially is a set of the smart contract which mainly focuses on transferring tokens issued on Ethereum blockchain from one person to the another, without racking up high fees or time delays.