Lego 8638: Cars 2 Big Bentley's Bust-Out

This set allows you to build Big Bentley, the Cars 2 version of Big Ben, as well as 7 other characters from Cars 2: Holly Shiftwell, Finn McMissile (British Intelligence), Mater (average intelligence), Lightning McQueen, The Queen, Miles Axelrod and Professor Z. The small cars were the easy part, Big Bentley as difficult. It required many specialized pieces (not traditional bricks at all) and some features were quite complicated, especially the pulley to hoist Mater.
That was a really cool feature because I like the Lego sets that can actually become toys once you've constructed them, as opposed to just sitting on a shelf collecting dust, or being quickly deconstructed into loose bricks. But certain parts of this were well beyond the skill level of a 4-year-old. I know the box says the recommended age is 7 to 12, but are children at the upper end of that age range really into Cars 2?
I'm not complaining about it, I enjoy building with him, letting him do some, and I do other parts, just echoing a concern I've read elsewhere.
Overall, this is a really awesome set, worth the $50 or $60 because it is fun to build and fun to play with.