nice idea, i think it looks a bit too much like a orange mobile phone advert for me though, bit too crisp.
some off the stuff in the happy world doesn't look happy, the ice cream with a bite out of its head, the thing with the exclamation mark above it, and a strange tentacle thing.
The top rainbow is a bit longer I think- if they were the same there would be a better sort of symmetry to it- same with the cloud position. Also, maybe extend the ground out to the left, for a better composition? Like the characters. this is looking great
lol is that Rosewood I see? Just noticed your sad rainbow dark green is perfectly in tact on one side. Might want to muss it up to match. Otherwise, awesome!