Although this is undoubtedly a kid magnet attraction and very cool if done properly, as a parent I see a serious safety flaw in this design. You see the bookshelves going all the way up to the ceiling? You see how the vertical netting stops at the shelf above the window? There is a what appears to be about a two foot gap between the netting and the wall that a child could easily climb over and fall about twenty feet to the floor below. Looking at the one pic from below you can see the gap clearly. This would be bad for a smaller child that was unaware of the danger, or for a visiting friend of the twins. Additional netting is needed to insure safety.