I attended a meeting of an HR group the other night and the speaker, who was delightful and well informed, talked about giving feedback. She felt the word feedback was less onerous than using the word criticism. She also believed it is important to "sandwich" the negative feedback (criticism) with a positive before it and a positive after it.
While I agree that doing that softens the blow - I believe it is not always appropriate to soften it. Sometimes you lose the message in the kindness - because you are actually giving mixed-messages. You can be direct, clear, articulate AND kind at the same time without having to cloud your message by sandwiching it in-between two other items.
What I believe is that there is no one way. It depends on the people, the behavior, and the context. If, for example it is the first time you are correcting someone about the way they are performing a task, you would probably use the sandwich method. On the other hand, if someone was doing something against policy that was clearly inappropriate, you would not want to soften the message. You would want to firmly state that the behavior was inappropriate and needs to stop.
We give feedback about minor things that are changeable. We offer criticism when we want something changed right now.