I use this as an addition for my system, it's great for daily checklists and daily actions, it's very simple and i dont keep any dates or contexts there. I check it only once a day but everyday.
Here is an example of what stuff i keep there:
* sleep at least 9 hours each day
preferably 10+
* add even obvious projects and actions to Omnifocus because otherwise you might not trust it when choosing what to do
and so on, I got 16 items there overall, most other stuff is too personal and sounds too silly (even those 2 sound silly) but it helps.
i use omnifocus for projects and actions, and project support is in mind maps and evernote so Reminders is just a small addition but I find it very useful and convenient for simple checklists which you want to keep separate from next actions/projects or calendar.
Not everything is a next action or project or area of focus and etc. so such things have to be kept in a separate checklist.
For daily actions I find it easier to use a separate daily actions checklist instead of using calendar or setting repeating actions with due dates for every single day in omnifocus.
Im also interested in what Kelly is going to post about using Reminders as a tool for GTD, I can see how it could work if you create separate lists, separate project list, context lists, waiting list and so on, seems very similar to paper system, it wouldnt be as flexible as omnifocus but might be easier for a beginner in GTD because the app is very simple.