I've always given a fair review regardless of how I acquired it... Gift, bought, free from company etc
I look at it like this.... If a friend took me for a meal, and the steak was chewy, I'd still complain. Only reason I wouldn't complain, would be if the person I was with insisted I didn't.
I used to be on the customer panel for the local bus company. As a perk, we received a bus pass. However, that didn't stop me from adding to the forum n complaining as needed.
If you are true to yourself, you'll always be honest... Ain't saying tiny white lies don't happen now n again, but never to compromise my reputation.