I have to start this review with a disclaimer.
Initially, there were movie tie-in novels for the movies in the Marvel Cinematic Universe... for Iron Man and The Incredible Hulk (both were great by the way). Then, the movies instead had junior novels for the tie-ins... but really - these junior novels only tell "half" of the story. They're more like teaser novels. I'm sure that's the point - release the book a few weeks before the movie... people will read it and want the rest of the story. This Bumblebee junior novel is like that - not the whole story.
What is in the book is enjoyable for a quick junior level read... I don't want to spoil any details - there were a few instances where the book has material not in the movie... I wonder if there may be some deleted scenes on Blu-Ray and DVD... The first of the two relates to the girl Charlie Watson, and it's fairly powerful... so it's a shame that it was not included in the movie - the other was just not needed.
So, in my opinion, this book is good but lacking... If you want to read the book before checking the movie out, I don't think that you'll spoil the movie in the least. The movie is what long time Transformers fans have been waiting for... As a child in the 80's and having watched the animated series and having some of the toys... Yeah - go see the movie!