It truly is. It fits perfectly in one hand without stretching uncomfortably, so I can hold it for longer than any reading session I've had without making my hand get stiff. While holding it in the normal way, my thumb naturally rests on one of the side buttons, which I've mapped to "next page".
If I were to hold out my hand, and someone put an X4 in it, I wouldn't have to move a muscle and it'd be in the right position for me to read for hours with just the periodic button tap.
Everyone's different, of course. It's guaranteed to be too big or too small for others, and that's cool. For me it feels like someone custom designed it based on a model of my hand.
I've merged some working PRs onto my device and it's working great. I really needed a dictionary option because I like to quickly know the meaning of words as I read.
its fine. theres a few more things that could be nice (reading statistics for example) that other forks do have.
This. The form factor is almost the right one for an e-reader. The battery lasts for weeks. It is so open that you could probably write your own firmware for it based on CrossPoint or similar for your own needs.
Needs some iterative development while ruthlessly culling requests for random features.