I've been using the RM1 for a few months. The screen and UI responsiveness are both fine. What is astonishingly slow is their ereader implementation. Basically, the model is something like this:

• The ReMarkable is primarily like a sheet of paper you can write on (or a paper notepad).

• This "sheet of paper" can also have a background template (like dots, a grid, or an arbitrary image), different for every page. (You can add your own images/templates onto the device with scp and editing a JSON config file.)

• When you read PDFs on it, each page (at your specified zoom level / crop region) is rasterized (reasonably quickly) into such a background image, with the result that you can write on the PDF page if you want. (These won't be "PDF annotations" in the PDF-standard's sense AFAIK, which some people complain about: it's just like writing/drawing on some image. But you can export your annotated PDF as PDF/PNG/SVG.)

• When you read EPUBs on it, the whole epub gets converted by some incredibly slow process into the equivalent of what it does for PDF (my understanding is that it's basically rasterizing each page). This means that if you're reading an EPUB (that you downloaded from the internet or transferred from your Kindle or whatever), and you do something as simple as changing the font size, you can expect it to take tens of seconds(!) even for a small 200-page book, as it's "regenerating" an image for each (resulting) page of the book. Once that is done, though (i.e. you don't change/resize font again), it's reasonably quick and straightforward to use.

So, now, I don't bother with trying to read EPUBs on the device; I convert to PDF first on my computer (where I can more quickly and interactively tweak font size, page size, etc), then read the PDF on the device. That works very well.

Ah, ok, that is slow, but makes more sense if it is processing the entire book vs just the page you are on. Thank you for explaining further how it works. Still piques my interest - and would be nice to be able to templatize some scaffolded notes (i.e. daily planner, without having to re-buy physical notebooks)

I'm not quite sure what you mean by the PDFs and EPUBs being rasterized - that's always happening with anything that is displayed on a screen. Do you mean that it is converted to a raster format and stored like that? (outside of a frame buffer that is)

Yes, there seems to be a cache somewhere. They have a nice trick: when you flip pages, a lower-resolution cached image renders and you can immediately start reading/writing, before being (almost immediately) replaced by the actual-resolution one. (See about 15:15 to 20:00 in this video: https://youtu.be/YWLJPyTrHnM?t=915)

For PDFs, any chance you’ve tried reading science journal articles on it? I’m thinking this could be a great way to finally get a greener way to read on paper without printing, but I’m worried its still annoying to do.

Yes, I've read quite a few maths and CS journal articles and conference papers on it, including some two-column ones. Things I'd have previously printed on paper. It's a good substitute (I'm happy, and I'm reading more, as this device can help me stay away from laptop/phone), with a couple of caveats:

- The screen size is slightly smaller than a regular A4 or Letter sized sheet of paper. You can go to "Adjust View" on the reMarkable and choose a smaller region of each page to fill the available screen (i.e., get rid of the margins and header/footer), which increases the size a bit.

- Academic papers often have footnotes / references on the last page or two, and if you care about them you'll want to flip back and forth (or in some cases you may also want to flip between two separate documents), which is quite a bit more annoying on this device than it would be on paper. Using https://github.com/ddvk/remarkable-hacks adds some features that make it better.

On the plus side, on this device I feel more free to write on it and mark up etc (can always undo / erase cleanly), while on paper (even printouts, let alone books) I somehow hesitate a bit more.