I think it's easy for people who looked up the star locations online to think that finding them seems impossible. In fact, there are clues that will lead to the stars, but you have to look very closely, and you have to have the attitude that *everything in the game has a purpose*. For example (extreme spoiler warning): why are there bits of extra platform here and here? What's this extra stuff over here? Why is there a little ledge up here? When I found clues like this, it reminded me of the Asimov quote: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...'"
When I was searching for the stars, I sometimes thought of the trick first, before solving the puzzle. When I found a really neat trick, like bouncing a goomba on my head repeatedly, or rewinding time to get a double bounce off a different goomba, I had the feeling that, "If Jonathan Blow didn't use this trick in a star puzzle, then he made a mistake and missed something really cool." Once I had that feeling I knew I was on the right track. One aspect of scientific research is that you don't know where to look -- but you are guided by certain aesthetic feelings, feelings of elegance or beauty that suggest you are going in the right direction. I think Braid captured that experience.
A friend of mine and I found all the stars (except world 3) without spoilers. In my case, in order to find the stars I had to become obsessed. There were entire days when it was difficult for me to stop thinking about where the stars might be. So, through the gameplay itself I experienced Tim's obsession -- I became just like Tim searching for the Princess. That's one way I think Braid is a brilliant game. And it didn't feel like a waste of time. I felt like I was honing my problem solving skills, and learning to be more observant, in a way that would translate into something useful outside of Braid.
I suspect that Jonathan Blow himself doesn't realize to what extent searching for the stars makes your brain tuned in to finding subtle things in the game that don't seem to have a purpose. Jonathan Blow never got to search for the stars himself. After one has found all eight stars -- and learned to look *really closely* for things in the game that don't have a purpose -- there are certain things in the epilogue that will just drive you crazy. Why is the first set of books sparkling green? In Braid, nothing sparkles green without a purpose, or so I thought. What is the purpose of the epilogue cloud and why does the epilogue block artwork show a book and a coffee cup melting through a table? Why is it possible for Tim to fall through the moving platform? To be even more obsessive: What's the purpose of the purple curtain and the wooden structure? Why must Tim be facing away from a red book to trigger the Om sound? Why is the Om sound not used in a very interesting way in a puzzle? Isn't it tempting to reverse time while the Om sound is playing, changing the octave? (You can only change the octave for the Om sound coming from the book that is not sparkling green -- this confirms that the Om sound is coming specifically from the book.)
I want to preface this by saying that I think Braid is a work of genius, a masterpiece, including the epilogue, and that it has elevated video games to a higher level, etc. But in my opinion, if someone were going to criticize Braid, this is where Braid is most open to criticism. For someone who has found all the stars without spoilers, these weirdly tantalizing clues in the epilogue hint strongly at the existence of some secret puzzle. When I noticed these things in the epilogue, I felt that if I didn't pay close attention to them, then I would have failed to learn the lessons that Braid had worked so hard to teach me. I spent days or even weeks wondering if I had missed something in the epilogue. If I hadn't seen the talk where Blow says the cloud serves no gameplay purpose, and the
where Blow says that there are some optional puzzles in Braid that don't give you acknowledgement -- and that for mature gamers, appreciation of the situation is the only reward you need -- then the epilogue would still be driving me crazy. So, if one were being critical, then one might say, "Braid treats your time and attention as precious -- except in the epilogue, when the game sends you on a wild goose chase."
I think the melting table artwork did have significance -- if it didn't, then Blow might as well have shown us a picture of a spork. I think it was hinting at the ability of Tim to fall through the platform, and that the main point or "meaning" of Braid is to make discoveries like that. I was thrilled when I discovered the trick of falling through the platform. So I thought the epilogue was awesome, even though I'm saying I think it's open to criticism.