A critique is not the same as criticism. A critique is about helping someone improve their work.
Saying to the person you are reviewing that "your work stinks" is hurtful and unproductive.
Instead, you should:
Always begin by pointing out what's working. Be as specific as possible, and explain why. Just saying "I like it" and nothing else is not productive.
Point out what isn't working, and why. Be as specific as possible, and explain why. Provide suggestions for how the person could improve their work. Just saying "I don't like it" and nothing else is not productive.