Am I wondering how can I validate simple money transfer from one address to another? I'm querying the blockchain with etherscan and have transaction hash. Is it enough just to check from, to and amount, or I need to check something else?
You should also consider a number of validations to make sure the transaction is final.
Have a look at this very good reddit thread regarding the recommended number of confirmations.
If you're receiving small payments, with low chances of fraud, then yes, you can assume that what etherscan shows is correct.
If you're handling large amounts, with high chances of frauds, then the same thread recommends you to wait for 12 confirmations and to:
exchanges and entities handling very large amounts of Ether frequently are still encouraged to run two different Ethereum implementations and only accept transactions that have been confirmed by both for maximum security (e.g. Go & C++).