8 year old level that 6 year old completed

I bought this set for my 6 year olds birthday. I know that the recommended age is 8+, but I felt that the challenge would be good. He had previously completed LEGO sets and was getting better at following the directions step by step. When he opened his gift, he lit up. I knew I did good! He was so excited to work on it. He worked on it step by step and did not need help for any part of this particular LEGO set. 19 hours after starting, he completed the build. Obviously he did not work 19 hours straight on the set. That 19 hours included dinner, a few hours playing his new video game he also got for his birthday, and sleep. So I'd say about 7-9 hours actually went into build time. For a 6 year old to build a recommended age of 8+ set in that amount of time, I'd have to say instructions were spot on and easy to comprehend. Now that the initial build is done, he is enjoying playing with the characters from the set and combining them with those from other builds. I am so pleased with my purchase of this!