We were about to run our project on Ethereum.
After hard fork I'm not sure it is a good idea.
I don't understand how can anyone use blockchain which could be hardforked by creator's decision.

Vitalik does not decide, the Ethereum community decides if they want to hard fork or not. The miners decide.
Yeah, right. VB was able to stop ETH deposits and withdraws at the exchanges with a conversation. The soft fork is opt-out, not opt-in aka default for the update. VB and his buddies lost coins so they will push everyone to "fix it". ETH is probably the most controlled coin out there. What good are ETH contracts if they can be reversed?