This book and the subsequent ones are again victims of the magic of having read them as a child and loved them. I discovered from personal experience that a positive experience as a child builds a positive experience for life and a negative experience can prove negative into the future. For instance books I loved then I still love now. And also because of my negative experience with costumed gorillas and clowns I still think that clowns (and clown-like dolls) are the creepiest things in the world.
Anyway that all said I loved this as a younger child and I still have fond memories of it. It featured the idea of two parallel worlds for a younger audience and yet created a story that my parents also liked even my Dad who doesn't read as often as I do and generally doesn't read fantasy style books.
The premise of this book and series follows one boy with a medical condition who passes out across a divide. As a result he ends up in another world. And this world is one populated by brownies, gryphons and all sorts of magical items. But where science works in our world in this one it does not. Which makes science like magic in this different world and magic like science. Which of course was very interesting to me.
I may re-read this in the future. I've already re-read the trilogy at least three times (I got into a faze where I re-read all the good books I had read a lot of times. So I've probably read most of my old favourites 2 to 3 times and maybe even 6 times depending on the book). Either way it remains in my memory as a charming novel that deserves to be better known.