It would have been nice if the man who worked for Billy's grandmother had more explanation included about him. His ability to travel between worlds was made clear, but his purpose was not fully explored. It also was somewhat strange that even though Billy didn't seem to really know his grandmother since he mentioned recognizing her from a picture, that he talks about how she never mentions his grandfather. If he doesn't really know what she looks like, it likely stands to reason that he wouldn't talk to her much and therefore wouldn't know how often she talks about his grandfather.
The story uses simple words, but the author is a pre-teen girl, so this is not so unexpected. Even though there were times when more complex words may have helped the story become stronger, the simplicity of the words reflected the simplicity of the characters, and how they themselves didn't know much about their surroundings but were trying to make sense of it all as best they could. This is definitely a positive aspect of the story, as kids and pre-teens will find a stronger connection with the story and the ease with which it can be read and enjoyed.
In all, 'The Pathway to Dragons: The Portal to Pyranis' provides a welcome escape for readers who love mystery and fantasy. Hopefully Hoffman will continue her writing about Billy and the underwater archway that transports him and his friends to Pyranis. There are definitely more stories that can be told to explore everything Pyranis has to offer as well as Billy's family relationships.