For me, I would really appreciate honesty and integrity. If something is bad or good, just give your honest and polite opinion on it. You do however need to be tactful and specific about what exactly the problem areas are. "This game is bad" isn't helpful, "the controls feels clunky/unresponsive" is better as it gives an indication on how to resolve the issue.
This aligns well with you viewers expectactions, they want to know if the game is good or not and they need to be able to trust that what you are saying is the truth.