The concept of Siacoin itself is unique because it offers storage at low cost to the crypto community.
The user can use the Siacoin cryptocurrency to carry out the peer-to-peer transactions. Unlike bitcoin, this has been employed for making transfer between the host and the user.
It has also employed the application of contracts which can be quite similar to the smart contracts on the ethereum. These contracts ensure the terms between the user and the host and of the payment as well.
Siacoin provides for the most secure and cheapest platform for cloud storage. The long term motive of the developers of Sia is to give tough competition to the already existing cloud storage platforms in the market.