Backpacker Flip F.
Google
Interesting idea, but not worth the entry fee. The Happiness Museum has some thoughtful exhibits about the science of happiness, and I especially loved the room where visitors leave sticky notes about what makes them happy - sweet, personal, and heartwarming.
However, the museum is very small and can be seen in around 20 minutes. For the price (~$17 USD) it felt more like an extended infographic than a full experience. It also felt like some of the information was outdated (up to 2016 US Election seemed to be the latest noted date/event in the formal exhibition).
This museum is worth a visit if you're really into psychology or Danish culture, but not a must-see in Copenhagen