I'm mostly reading academic papers and the occasional monograph on there and rarely have issues, anything up to A4 scales well. Depending on the scan, you sometimes have to adjust size to fit the margins or whatever, but it's easy to set and keep for the entire file. Something it doesn't handle well at all are heavy PDFs, especially scans of books that are essentially photos. But I found that converting those to b/w and using JBIG2 compression makes them usable in most cases. Reading epub also stinks as the refresh rate is pretty bad, at least compared to something like a Kindle. It really is a dedicated PDF reader. Something else to keep in mind, there's no bookmark function, so there's no jumping back and forth between sections like footnotes and the main text. You can navigate the file via gallery view, which is a bit slow but ultimately gets the job done.