Yes, the world of apps are crowded. I had my choice of 8 metronome apps and those were just the free ones. And yes, many apps have one neat feature that grows old. The vuvuzela app that I had for all of 2 days would fit that description.
But the Beer in Japan app (an offshoot of the website of the same name) is in a small niche and it is useful.
You can plan your trip and then use it when you are in Japan to take notes too! It doesn’t require wi-fi and it has coupons!