Just finished Braid.
The last world (perversely named "World 1") sucks a bit unfortunately. Up to then I had more or less ignored the nonsensical storyline and concentrated on the clever puzzles. In the last world the clever puzzles take a back seat and the nonsensical storyline gets rammed down your throat. Well I finished it and I read every word of text in the game and all I can say about the story is: "It's nonsensical".
Its a pity that the game ends on such a downer because it really is a beautiful piece of work.
In the interest of honesty I must admit to having cheated twice. I read hints for two jigsaw pieces. I'm not proud of it but I ran out of patience. One of the times was a head slapping "Aghhh ... I should have known that" moment but the other was one of the trickiest puzzles in the game (the middle puzzle piece in the "elevator action" level). I don't know if I would ever have spotted the trick left to myself.
Edit: I have just read a bit more about the game and I realise that there are a few easter eggs including a secondary ending. Apparently you can only get that if you find some hidden stars before you complete the third world which means that it is completely blocked once you finish game normally. Bizarre game design. I certainly amn't going to replay the game just to see it.