Screenshots looks nice. Maybe you should focus more on the differentiating aspects? The note-taking application market is extremely crowded.

(which is indicative that the issues are human, rather than technical — people feel the need to record stuff, but are not really able to stick with it and get good results; I have a stack of paper notebooks where I tried different systems as a physical manifestation; the software cemetery is less visible, but no less extensive. I may have found my final system, but who knows how long it will stick…)

Are you targeting per-project, short-to-medium term notes? If you have “second brain” ambitions, and choose to provide a hosted solution with no standardized format for export, you have to have some sort of long-term commitment. I do not see how that commitment can be taken in a way that is credible.