Feedback for another user can be viewed via the Insight view page only. However, visibility to all feedback is completely based on the permission setup of your UpRaise. Depending on your UpRaise role, your admins can create a setup and can define if the other's feedback should be visible to you or not.
As a non-admin user, if none of the feedback visibility permissions are set to true for you, then feedback is visible only if it is explicitly shared with you by the feedback creator.
Exception is super admin - super administrators on your instance will have access to all feedback messages, irrespective of whether they are shared with them. Whereas, admin can view other's feedback when they are creator or are in shared with list.