Well, actually your competition isn't Post-it notes or email, it's online calendars which can be updated from a phone or a desktop computer. Some people will be hesitant to use the cloud but then email would also need the cloud.

I'm not sure if I agree with this: online calendars work very differently than Post-It notes or FriendlyStack Reminder. With online calendars, you either have to remember to check them to see if you forgot something (a weird concept) or have them remind you that you forgot something when you have no time to deal with the issue (and thus will ignore the reminder). Post-It notes and FriendlyStack Reminder, are placed in strategic locations, right in your field of view. You see them, dozens of times, day in and day out, until you are ready to take action!

I do agree, that using a (cloud) service, which you don't control, requires a certain level of trust. Using standard email gives you freedom of choice regarding your service provider and your preferred email app. You don't have to trust the big data-hungry ones nor do you have to get used to a new tool.

After all, this is exactly why I developed FriendlyStack Reminder the way it is!

Mmm, my calendar reminds me 15 minutes (can be chosen, and with a variety of notifications) ahead of time of the event for things that have to be done at a certain time. There are also all-day-events. If a reminder persists you can make it a task which sticks around until you dismiss it. As for being in the field of view, checking the calendar is just part of checking the phone for the time, weather, etc. It's also integrated with my desktop so I see notifications while working there.

Calendars are available from a variety of providers, including the ones that provide email. You can use a different provider from your email provider too.

Online calendars can also receive inputs from sources like online bookings and email, no need to transcribe.

It's integrated with a device you already have so no extra device needed. This is the main objection: Yet Another Device to Carry Around. Of course if you don't trust or carry a phone, then maybe FriendlyStack Reminder can do the job.