Ethereum isn't my project. I build apps on top of it, like Augur. I'm claiming that work other people did will be pretty huge for humanity, which I consider pretty acceptable.
What questions do you have about how Ethereum is useful? I attempted to answer that question, but appreciate pointers that would make it more effective.
I think that after explaining a somewhat complex subject like how Ethereum works, you perhaps could followup with a clear example on how Ethereum solves a problem that other technologies would have a hard time doing.
Maybe you can talk how Ethereum can be useful for, if I understood the platform correctly, buying/selling a car by means of a colored coin.
Or maybe you can explain how it competes for buying/Selling money Bitcoin-style, but with the specific advanteges pointed out (e.g. you don't have to download the blockchain as far as I know, etc).
Edit: After going through a few explanations, this one came up as the one I would think of using to someone that already knows Bitcoin:
Blockchain technology, introduced by Satoshi Nakamoto with the proof-of-concept implementation of a simple value transfer system known as bitcoin, represents the best digital system we have (after the internet itself) for administering multi-user interactions without any need for centralized coordination or oversight. Effectively, a decentralized system is its own authority for enforcing the rules (e.g. 'you can only spend your money once' in bitcoin, or 'whatever rule you programmed in to your smart contract' in Ethereum)
So Bitcoin enforces a very specific rule, Ethereum generalizes by letting you specify complex rules and even composite rules on top of that.
What questions do you have about how Ethereum is useful? I attempted to answer that question, but appreciate pointers that would make it more effective.