Gallon is pretty but not super helpful. – 1 Gallon a Day Review

Reminders are great, UX is easy, and beautiful. However even going "pro" you can't customize the size of the glasses/bottle you use. Which is the functionality you think you're getting when you purchase it. If the point is that this is supposed to make tracking your water intake easier- let someone who paid 1.99 for your free app put in their own number of ounces for a water bottle. And I don't know anyone who actually has 8oz glasses.
Review by techierain on 1 Gallon a Day.