Looking at all that Seoul had to offer for kids, we added this to our list of things to do. It was a great experience from start to finish. The guy who does the safety briefing and stretching made it fun in several languages, and this helps to space out when you enter the maze, so that you don't run into other people.
Inside the maze are all kinds of physical and mental challenges, which are great for ages 7-12. If you are a parent, be aware that you will need to be average size or smaller to get through some of the elements. I am 165cm and 60kg and felt 'big' in there. As someone said in another review, if you are OK going through a McDonald's indoor playgym or equivalent, expect some of that here.
Some people have grumbled that the maze doesn't take very long to finish, which is true, but that said, if it were twice as long, it might have started to feel onorous. Maybe the ideal solution would be to have two mazes, so that you can do one, take a break, and then do the other one. This attaction is partnered with a trick-eye museum nearby, so I can see how the two of those activities would fit together nicely. We didn't have time to do that on this trip.