I like the artistic touch in the standard challenges presented under the link "Practice" in the main page. We can find few puzzles and tasks well illustrated and having tests, I really enjoyed solving them from time to time because it's beautiful, clear and instructive.
But those days, and after returning from a long period of absence, I found the "Standard" Practice Challenges crowded with players or community puzzles not having a good visual design and adding noise to the old puzzles. In the past, I showed the site to a friend and he appreciated the old list of games with their graphics and animated tests, but yesterday, when I showed it again to another friend he noticed that it's so noisy and crowded as if it's an amateur forum or exchange list.
I assume perhaps you are trying to promote players contributions by putting them at the same level of the standard challenges, but in my point of view, it did add creepiness to the old enjoyable list. Maybe you can put them in an other tab in order to preserve the beautiful graphic style in the already exiting puzzles.