Good but not Euclidea
But the elephant in the room is Euclidea. Not really fair to compare the two but many people will. I learned some geometry fundamentals from Euclidea. Some of the pyth60 puzzles are hard but I don’t think I learned anything. I passed up pyth60 for a long time, thinking the concept seemed a bit contrived, and IMO that instinct was correct. I worked through all the puzzles for a complete review. Some were just tedious - I used a calculator on several, and resorted to a spreadsheet on at least one centroid.
So, challenging if you’re in the mood, and moderately rewarding.