Our bright 5 year old son really had problems with Giant Jim and Tiny Tim; he was clearly very confused and upset while reading it, and we have to sympathise with the lad because it is a very odd book indeed.
The premise of the book is that Giant Jim has a tiny friend called Tim. It’s centred on a pun where Giant Jim wants to be “in” the book but he can’t fit onto the page because he’s drawn too large. We had difficulty understanding this joke on first reading, but realised eventually what the point was meant to be. The Giant is supposed to be trying to fit onto the page feet first, then hands first (!), then head first, all without success. At the end, it just stops with a sort of post-modern irony which goes over our heads, let alone a 3-5 year old, the age group at which the book is aimed.
Our son absolutely did not get the point of the book. He became increasingly distressed while we were reading the book, because he wanted to read it, wanted to understand it, but could not. The same joke translated to 3D he found hilarious; his dad showed him the same steps in him trying to fit into his bedside table drawer and he totally got the joke. When he said that the book was trying to make the same joke he said, “But it hasn’t got any sides. It’s flat.”
We have no idea whether most four/five year-olds would have trouble with the subtlety and irony of this book, but this was our rather perplexing experience of it.