P.B. Winterbottom is a dastardly pie thief (just look at the top hat and mustache - how could he NOT be dastardly) who, in the midst of one of his greatest heists somehow taps into the time stream. I won't go any further, other than to say Winterbottom can be in multiple places at once. Not a bad trick, especially if you're a thief.
Winterbottom's adventure through time is split up into five areas, each with ten levels. The setup is similar to Braid. Each set of ten is built around one concept; beginning with a simple application and eventually growing into a multi-part brain-buster. For example, one group may revolve around pies only Winterbottom's clones can reach. One puzzle may involve using a clone to enter an area while Winterbottom holds down a switch, while another may involve setting up a complicated Rube Goldberg device involving multiple instances of clones set up in an elaborate pattern.
There's plenty of variety in puzzles. New concepts are introduced just as fast as they're thrown away. This helps keep areas fresh and offers some motivation to keep moving forward. Though you may quit because you're stuck on a puzzle, you'll rarely stop playing out of boredom.
Playing through Story levels unlocks Challenges, which are much harder than those you'll find in Story. Well, almost. The catch to Challenge missions is you're rated based on how many Clones or how long it takes to complete a level. They may look simple on the surface, but add a time limit and you suddenly get really stupid with choices.