The discussion centers on finding the best portable device for reading mathematical PDF files, emphasizing the need for clear display of equations and graphs. Users express that Kindle devices, particularly the Kindle Touch, are slow and not ideal for PDFs, while tablets running Android or iOS, such as the iPad and Nexus 7, are recommended for their superior performance and display quality. The Nexus 7 is highlighted for its ability to handle large PDFs easily and its high resolution, making it suitable for math texts. Some participants prefer e-ink readers for their eye comfort but acknowledge the limitations in navigating complex documents. Overall, the consensus leans towards tablets for their versatility and ease of use in reading and studying scientific materials.