The cloud sync service for Things is now in public beta. For those who currently use Things, there is a special beta Mac app that you have to download and you can’t just migrate over your current library and flip on Cloud Syncing for it — you have to start a new database and manually enter in new to-do items that you want to sync via the Things Cloud.
And note that the beta Mac app has quick entry disabled by default. You can enable it however by running this command in Terminal:
defaults write com.culturedcode.things_beta QuickEntryEnabled -bool YES