My wife and I love to quest together but sometimes it gets frustrating not knowing how far along the other person is with a quest. By default WoW lets you see some party information in tooltips over mobs and other quest items, but that only works if you aren't done with them. If you've collected all the seeds you need then you can no longer interact with the seeds. This makes it so you can't tell how far the other person is without constantly asking them. Likewise, I have flying in all the zones and my wife does not so we are often flying around in my passenger mount together. I find I'm constantly having to ask whether or not she's turned in and/or picked up the same quests as me because we can often do that without dismounting so it's hard to tell.
We find it relaxing to quest and listen to audiobooks or podcasts and this addon helps to eliminate some of the superfluous conversation without having to constantly pause our shows and communicate this basic repetitive information to each other. Ultimately we plan to have a custom quest log that will notify the party when it is out of sync, but for now the basic features are limited to reporting information to party chat.
The screenshots here show examples of this text in /say chat even though the addon is designed to report to /party chat. This is because the addon was running in debug mode to provide the screenshots. The standard behavior is that the addon will silently keep track of quest information in the background and will only report this information when in a party with someone. In the future we'll be adding an options panel to configure things like this. Eventually we also want to add the ability for the addon to communicate to others with the same addon using a custom addon channel. This will allow us to report others' quest progress to you without cluttering chat channels; it would even allow strangers to quest next to each other in the same area and see the others' progress as they go!