Based on the users' reviews of the Block Knock app, here are three cons and pros: **Cons:** 1. "Disappointing experience. Ads are invasive and often crash the app." (15 words) 2. "Limited functionality. Users are disappointed with the lack of features and customization." (15 words) 3. "Glitches and bugs. Frequent errors make the app frustrating to use." (15 words) **Pros:** 1. "Simple yet effective. Easily block unwanted numbers and contacts." (15 words) 2. "Intuitive design. Users find the interface easy to navigate and use." (15 words) 3. "Good customer support. Developers respond promptly to issues and concerns." (15 words) Please note that these are general summaries based on a sample of user reviews, and may not reflect the full range of opinions on the app.