There's a constant low-level chatter on the net about critiques, about being "nice," about unfair and vicious reviews and the ubiquitous mean people. I'm of two minds about this. I believe in honesty. I believe in not taking things personally. I believe in karma and I really, really believe in paying a compliment when you feel one inside.
People have thin skins. There's a constant barrage of negatives in this world, and it's really all any individual can do to counteract that. To that end, I like to give compliments. If someone looks good that day, I like to tell them. If their eyes are pretty, if they did a good job, if I'm proud of them, if I'm simply grateful they're in my life, I like to tell them. It's important to have the folks in your life know, without a doubt, that you DO recognize the good in them.
Don't be stingy with your compliments. Let them flow. Watch other people bloom under the freshening power of your good words.
On the other hand, I have to say it again, I believe in honesty. Speak your truth. If someone is upsetting you, tell them. If someone does something objectionable (wrote a bad book), it's all right to say so. That's not to say it's all right to attack the person (author), but it's more than fair to critique and dissect their actions (work). Don't let someone get away with bad behaviour or treating you ill - speak up and let them know how their actions affect you.
But, one of the things we don't realize is that if we make a conscious effort to speak a compliment whenever we feel one, it gives our criticisms so much more power. The recipient knows you're not saying something bad because you dislike them - they trust your opinion, they already know all the many, many ways that you like and appreciate them - and the criticisms will be taken in the manner intended. As a means of improving, not as a route to personal destruction.
So, say something nice whenever you can. You never know when you'll need that pool of good-will to skewer someone in.