I got Up next but found it buggy so removed it.
I did however install Reminders Nano and think it it is great for a simple app. It syncs with iOS Reminders and you can complete them on the watch and then add additional ones via force touch.
We have a shared shopping list for home and I've been able to view and add items using Siri with great effect.
Highly recommended
Agreed. Reminders Nano is the "missing app" Apple would have created themselves. Up Next isn't worth the trouble.