First, the good news. This is just a brilliant idea, and leaves room for limitless possibilities to be explored in the imaginations of readers, as well as in future volumes of what, presumably, is intended to be a series. The tie to science is handled very well. For instance, Simon and his friends are able to move faster by locally and temporarily altering the laws of friction and gravity, and first-time author Michael Reisman provides just enough explanation of the real science behind that for it to make some sense. The metafictional aspect of having the Narrator become a character in the story adds yet another layer of interest and future possibilities. The story is exciting, the pacing is excellent, and it's loads of fun. Young readers will love it.
But ... the author makes rookie mistakes with his characters. The three lead kids are fine, if rather one-dimensional. But in a misguided attempt at humor, nearly all of the adults in the story act like moody, spoiled, snarky, and rather dim-witted children. They'd be unbelievable in any book, but as the masters of the universe they simply detract from the truly awe-inspiring ideas; It's simply impossible to take any of them seriously. The author has come up with a premise that has tremendous potential power, but then dilutes it with weak attempts to be silly. Your kids will enjoy it anyway, but this could be a series that rises to something far more than mere entertainment -- if the author can take some in-depth lessons on character before the next one is finished.