I like the his app, or I should say I like the idea of it. There are some inherent problems, however.
First: the app keeps kicking me out, and especially when I’m doing other things, I don’t want to have to take the time to log in, remember which username/password I used, etc.
Second: if I’m more unhappy/depressed, I’m much less likely to bother spending the time it takes to complete a short survey than if I’m feeling good. I’m sure I’m not the only person who experiences this and it automatically creates a user bias toward a higher average happiness.
When I was severely depressed/suicidal, I didn’t even bother opening the app. Now that I’m doing better, it feels like a lot of effort to log in every time so I just ignore all the notifications that pop up.
There were some other things I thought could be useful, like weekly or monthly tracking of specific markers of happiness, e.g.: family/career satisfaction, financial stability, interactions with friends, activities engaged in, etc. as well as things that might be correlated with happiness, such as alcohol consumption/drug use.