I bought this for my 9 month old granddaughter. It's easy to assemble and very cute. It's very spacious. I recommend at least 400 balls, I only got 200 and it didn't even cover the bottom of the pit. There were many adults (all different sizes and at different times) who were in both the ball pit and tent and showed up with my granddaughter. As for durability, there is none. So as long as the child doesn't try to stand up or lean against the wall, everything is fine. Durability, I've only had it a few months and have only used it a few times so far, but it's nylon so I'm guessing how durable you think it will be in the long run.