tl;dr: The Xteink X4 is a £40 pocket-sized e-ink reader with a crisp display, instant page turns, and a MagSafe mount, though its stock firmware is bare-bones. Custom firmwares forked from CrossPoint (Papyrix, Inx, MicroSlate, TernOS) unlock the device's potential, adding features like Knuth-Plass typography, Calibre/KOReader sync, reading statistics, and even writing or PalmOS-style modes. The author concludes that for pure reading, the X4's extreme portability beats larger or colour e-readers like the Kobo Clara Colour or Bigme B6.