No joke, no matter how predictable, was left unused. No plot development was in the least surprising. And the thing about big Rube Goldberg machines is that they're just not as cool when they're animated--- of course everything works.
I'm also confused at the ontological status of Rodney's creation. It's a robot, it has a personality. Doesn't that make it his kid? After so much overuse of the "hee hee it's really a robot" joke, I start to expect that everything in this world is animate--- heck, why not the pavement on the streets?
Probably great for undiscerning 5-year-olds. If you wanted them to grow up with short attention spans.