Based on the users' reviews of the "Mermaid - Hidden Objects" app, here are the conclusion: **Cons:** 1. Limited levels and difficulty progression: Some users felt the levels were too short and didn't increase in difficulty gradually. 2. Poorly designed gameplay mechanics: Reviewers criticized the gameplay mechanics, saying they were too repetitive and not engaging. 3. Frequent in-app purchases: Some users felt pressured to make in-app purchases, which they felt were excessive and unnecessary. **Pros:** 1. Engaging visuals and storyline: Many users praised the app's visuals, saying they were bright and colorful, and the storyline was interesting. 2. Enjoyable gameplay: Despite some criticism, many users enjoyed the gameplay, finding it relaxing and fun. 3. Easy to learn: Reviewers appreciated the app's user-friendly interface and ease of play. Note: Each of these points is within the 15-word limit.