I think this book would be a great introduction to longer novels- it's 146 pages, but there's a mix of pictures in with that, and relatively large writing. The narrative structure is also very interesting- the narrator occasionally switches focus from the main storyline to different perspectives within the story, or sub-stories to keep the reader interested. The main story focuses on Rover, a dog, and his owners, as Rover replaces Rudolph, and helps save Christmas. There's also use of information boxes to provide context whenever there's a thing in the book children may not be familiar with (for example, at one point in the book the pawpaw fruit is mentioned, and right there on the page below it, there's an information box saying what a pawpaw is, but with a humorous non-fictional information piece on potatoes, a concept the majority of children would be more familiar with). All of these add interest- there's no opportunity for kids to need to put the book down to go and find out what something means, and the added humour makes the book hard to put down anyway.
There's also interesting narrative structure in terms of differing lengths of chapters, with some, such as chapter 10 being just one page long. The book can appear to be random at times, with 'Commercial breaks' and random 'useless' chapters (Chapter 12 is only 2 lines long "I'm not telling. It's a secret". but I like this, I think it adds interest, and prevents any monotony that can come from a straightforward novel, especially for any children who aren't sued to such a long storyline.
Good life-to-text links, because obviously a core aspect of this book is Christmas, which most students will be very excited about. The book is also set in Dublin, with the weather being heavily discussed in the first chapter, which would also be relatable to children in England. There's also text-to-text links; there's the obvious links between this book and most Christmas stories of Santa and his reindeer, but there's also links to the other books by Roddy Doyle, meaning that children who've read his work before will also be interested.