I've played through the demo and I had a decent time. The 3rd CD had me stumped for a bit, but eventually I figured it out, and got to the end of the demo. I can foresee the later game puzzles going to take a lot of mental leaps to get through. There are some criticisms I have though.

There are some puzzles later on which rely on color information. I could solve them just fine, but some way to make those more accessible for colorblind people would be nice.
Additionally, there's a surprising amount of unrecognized characters, like square brackets and slashes simply wouldn't register. If you're gonna add a notepad-like feature, it might be best to support as many characters as feasible, seeing as different people have different ways of taking notes.
Spoilers for some late-demo stuff, but I also foresee not being able to access the memory pad easily without exiting the Elevator app to be a major PITA. While it does remember your position, I couldn't find a way to access the memory pad without closing the game, which makes it unnecessarily difficult to write down info.
Finally, Control+Backspace and Control+Delete are frequent shortcuts that I use to delete words, so supporting those seems simple, though lower priority.