Very useful technique. People can think you're wrapping the "bad" thing between two positive ones, but I see it as a way to encourage improvement.

We are more prone to remember negative feedback than positive ones, so we need to put the "negative" in perspective. It's something like this:

"There are things you do quite well, and there are things you need to improve. I've seen you can do better in X, but remember, this is just one. Don't identify your whole being with it, you're still good."

Thank you for sharing your insights!