Things on the Mac is my favorite GTD style to-do list manager. Their major drawback though, was lack of decent sync between multiple devices.
Well, they finally acknowledged the issue and promise cloud based sync to be available in a few months.
In the meantime, I move the Things DB to dropbox (launch the app while holding down the ALT key to do this). This at least lets me open the DB from different computers. But it can't handle concurrent edits, so be careful what you do! :p
Regarding iPhone & iPad, you gotta manually launch the app over & over again while on the same WiFi network for your stuff to sync... can't wait for this to end!!
Comments from long ago:
Comment from: Danny
I bought Things and the iPhone app and I regret it. The wi-fi sync is annoying. I had to figure out for myself that I have to close the app and open it again to send changes from my phone to my Mac. WTF? Also, it’s useless for working in a team and I don’t know if their new sync is going to add multiple users to address that. I’m looking for something better to use at work.