Hi everyone. I love Exercism. It is an extremely effective and fun way to learn. I just wanted to say that I found the ‘level of difficulty’ rating for some of the exercises was way off. Some of the ‘easy’ exercises were very difficult, and some of the ‘medium’ exercises were very easy. Maybe you cold get users to rate the difficulty of the exercise after completion, and things would self correct. Thanks.
Which track? Which exercises?
Exercises are rated on a scale from 1 through 10 then buckets into easy, medium, hard. Unless you’ve completed the hardest exercises, it’s hard to map exercises to values (since you’re not familiar with the upper bounds). Another tricky part of scoring difficulty is that difficulty can be scored on multiple criteria. CS students might think implementing a breadth first algorithm while non-CS students might have a hard time with the algorithm. Some people may feel implementing a long list of validation steps makes an exercise hard while others might think that’s trivial. Some people might thing matching brackets is very hard (and it is until you light upon the right algorithm) while others may think it is trivial (which it is with the right algorithm).
If you’re completed a whole bunch of exercises and have suggested updates for the difficulties, you can see if the track maintainers are interested in suggested updates!
Ah, that’s a neat idea! Truth be told, assigning difficulty to exercises is, well… a difficult thing 
because folks’ skill sets vary widely. But as you say, it would be interesting to see if a user rating system would cause the level to stabilize over time.