Evernote failed because their product was sub-par. Onenote always provided better organization, better pen input. There were just numerous places in which you could see that man-hours were being placed in the wrong places.
I should be a target for this sort of software and used something else in the same general vein for a few years. But I don't really like everything tied up in a proprietary format even if I can export bits and pieces to some degree. And more generally just tend to go back to text editors, word processing docs, etc.
Put another way, it's software that sort of demands 1.) That you want to carefully save/curate what you read and write for later reuse and 2.) You go all in on a particular program.
There's a total of twelve people listed on that about page, only three of whom are programmers. Most of them are also writers, including two of the programmers, and it sort of sounds like a lot of these jobs are part-time.
So yeah, definitely lifestyle business rather than unicorn.
I once read an interview with the founder of Genius, and something he said stuck with me: “I guarantee that 90% of you are working on the wrong things, and you think you’re working hard, but you might as well not be going to work at all."
Spot-on.