Based on the users' reviews, here are three pros and three cons of the Niggle app: **Pros:** 1. Simple and intuitive interface makes it easy to use for puzzle lovers. 2. Challenging levels keep players engaged and motivated to solve puzzles. 3. Daily rewards and achievements provide a sense of accomplishment and motivation. **Cons:** 1. Limited game modes and levels can become repetitive and boring quickly. 2. Some users experienced issues with in-app purchases and flakes. 3. Lacks a feature to track and compare progress with friends or global leaderboard. Note that the reviews are mostly positive, with players enjoying the game's simplicity and challenge, but with some complaints about limited game modes and issues with in-app purchases.