Yeah people. Explain Ethereum without using the words "smart contract" please.
Because the program author has no admin privileges, users don't have to worry about the service provider abusing their admin privilages to secretly modify the database (which may otherwise be a concern for high-value applications such as, e.g. vote-counting, e.g. a database that stores bank account balances, etc).
The disadvantages are (1) it is much more expensive compared to other cloud computing services, (2) since the uploader doesn't have admin access, they can't fix bugs, and since everything is transparent, it's hard to store secrets.