Skyworld first came out in Brawl, loosely based on the Kid Icarus games. Though when the later game, Kid Icarus: Uprising came out, you could easily see this setting in a game like that rather than the 2D games.
I've never been a big fan of the stage. It's small and simple, which isn't my cup of tea.
But I don't like how the platforms can be broken and a cloud takes its place for some time. It's hard to remember when to land or jump when the chaos takes place.
It isn't my most hated stage, but I've never been too happy to see it either.