Based on the user reviews, here are three cons and pros for the Threema On-Prem app: Cons: * "Poor customer support" - Many users complained about difficulty in getting help from the app's support team. * "Difficulty in setup" - Some users found it hard to set up the app, especially for large-scale deployments. * " Limited features" - A few users felt that the app's feature set was limited compared to other messaging apps. Pros: * "Secure and private" - Users praised the app's strong focus on security and privacy, providing a safe space for communication. * "Elegant and user-friendly interface" - Many users appreciated the app's clean and intuitive design, making it easy to use. * "Customizable" - Users liked the ability to customize the app to suit their needs, with options for group chats and file sharing. Please note that these are based on a limited sample of user reviews, and not all users may share the same opinions.