A good start, but needs a lot of work

Update: no significant advances to this app in years. No TouchID, no Health kit integration, no Siri integration, and the interface is still as clunky and ugly as ever.

This is the most flexible and potentially powerful app Ive found for tracking various aspects of my life. Unfortunately its got big problems:
UI design - the interface is unintuitive and clunky. It does not respect the design conventions set forth by Apple and used in other apps, so its often hard to tell what is a button or a text input field, and theres a frustrating lack of swipe options. I wish there were better options for visualizing all your data over time as well.
Sync - there is no syncing of settings and data between devices. This seriously limits its usage for me. Luckily you can backup to and restore from DropBox, but I dont know if you can do this across devices. You can also backup via email, but Im not sure what the use of this is since the backup file cant be opened by Excel.
Documentation - there is very little, aside from a tutorial. The User Manual and FAQ items within the app are empty.
Icons - there isnt enough variety of icons for all the things you might want to track, and most of the ones there are ugly or hard to read.

vnavone about Symptom Tracker by TracknShare, v7.1.3