Honestly, the book far outweighs the movie in amounts of happiness distributed. There is more of everything including plot, humor, and heart in the book. A read it till the end and find it's past one in the morning. It was worth the dark circles. A delight of a read with a pace that ambles by like an old friend.
I admit that I caught the movie version first. Not typical of me, since the book version is always better. Movies are great but you don't get the same feeling for the characters and in this case you get a weaker story on screen. The movie version is certainly a feel good romantic comedy. Yet, it lacks a few things from the book like the fact that the imaginary friend is an adult from the start. I suppose someone down the line thought it would be less weird/potentially creepy that way.
Truly though, it works. I mean it's not as if we're introduced to perverts here. Imaginary friends are not creepy no matter their age or gender or species. They fall under that category of magical helpers who basically can do anything they like and still be certified as normal. They key is the sincerity. If they weren't truly out to help their kid(s), then it would be unwanted attention or harassment.
Basically, Jane has an imaginary friend that has to leave her when she turns nine. It's one of the rules. Except that Jane is supposed to forget all about Michael so it doesn't hurt. She remembers him and he ends up seeing her as an adult. The story winds around why Jane and Michael are meeting for a second time which has never happened to any imaginary friend.
The magic is the best part in my opinion. Magic is best left alone and it is. Michael can just snap his fingers and things happen. He doesn't know why and can't explain it. Jane asks about it but there are no answers. The point isn't in the magic because it's all about Michael and Jane.
So, if you're looking for a love story without exaggerated drama and with a touch of magic, then this might be the perfect book for your next gloomy day. Not all stories have this much warmth without the cheese.