Do you have any constructive criticism to offer?

Meaning

Specifically asking for helpful feedback, not just complaints.

Examples

• John: 'I've completed the first draft.'
• Alice: '<b>Do you have any constructive criticism to offer?</b>'
• John: '<b>Do you have any constructive criticism to offer?</b> How can I make it stronger?'
• Alice: 'I've presented my findings.'