Every topic is its own flat file. Nothing is better than keeping your data in the file system with an option of git source control or online backup. See here.
The daily journal feature allows you to quickly capture disparate topics under today's date and by way of tags make things organized and findable from any topic page.
iOS app has a very clean UI .. on phone it is actually quite usable… just what you need to capture fleeting thoughts and notes. Not too many options getting in the way all the time.
Lots of apps are too graphically flexible in how they allow content to be entered, placed, and formatted. They act like Word when what you want when authoring content is Markdown. Content and semantic structure, not graphical frills.