It’s the wrong size. The E Ink display is greyscale. Zooming and panning are disruptive. A tablet probably works great, but I don’t know – I’ve never owned one. I solved the problem a while back when I discovered that I could simply rotate my laptop’s display via xrandr.
$ xrandr --output eDP-1 --rotate right --pos 0x0
Adding an autorandr profile for this makes it easy to jump to portrait mode. This is useful for reading any long-form content on the X260. Typing (or mousing) on the rotated device is difficult, so I’ll sometimes plug in my external keyboard if I want to do more than just page through a document.