Of course sometimes we get negative feedback too, which needs to be taken on board and dealt with. If you can see that the negative feedback is justified, and there is something you can do to improve the situation, then it is best to take ameliorative action as soon as possible. This means you need to understand what the feedback was criticising. Was the complaint about your product or your service? Was it about one specific thing or a general overall complaint?
If you are the one giving negative feedback, there is no point going off on a big rant about how stupid someone is or how hopeless their service or product is. Try to make your negative feedback constructive by referring to a specific incident or item, and how the poor service or product has affected you.
Best of all if someone has given you excellent service, or provided you with a superior product, why not give some positive feedback?