+ Very challenging even for those familiar with these types of puzzles
+ Calming, zen atmosphere
+ Always a logical solution, no guessing required

- Expanded note taking features would be extremely helpful
- Too easy to brute force your way to solution if you make a guess or wrong turn
- Hard too see where you went wrong if you make a mistake, makes learning more difficult than it should be
- Too much mental arithmetic takes away from the appeal of the logic