Very disappointing experience. I love technical assignments and I see them as a great opportunity to practice and learn. But when you put your extra time in such an exercise you would expect at least some feedback over your delivery, not a generic message like "Unfortunately your submission wouldn't qualify". I totally respect their decision, but even after reaching out to the recruiter they never got back to me with a more detailed feedback, so I can only consider this a lost of my time and a very bitter experience.