The pricing model is confusing at first and not very clear until you start trying to use the app (tried the macOS version for now). The App Store description does not mention the subscription and what features it unlocks, and in the app it doesn't trigger until you try to play a song. If you dismiss the window, you actually have to go back to playing a song (and wait) to see it again as there isn't a settings pane or other trigger just to see the subscription page. A few suggestions on that front:

  - Put the pricing either on a splash window after opening for the first time OR in a message tile on the library screen
  - Include certain (full) songs in the free version and give them a badge of some sort ("free", "included", etc.)
  - Put a badge in the toolbar indicating whether you are in a free or paid mode
  - Make it clear if a subscription is valid for iOS *and* macOS or if they are separate (2x the cost) (edit: downloaded on iOS and it's not limiting anything so it must be a universal subscription. Put that early in the description for sure.)

I put a piano in my apartment in 2020, the year the app appears to have been first released. Several people in my household were looking for something exactly like this to practice and never came across it, though we did get suckered into a few $10/month or $75/year subscriptions for other things that ended up barely getting used. If the pricing stays the same but is much clearer to people I believe you could get decent conversion from a little bit of targeted advertising.

Besides that, the import dialog could be less spartan. It is not indicated in the app itself that it takes MIDI files only. Normal users may not know what a MIDI file is at first but you might be surprised at how many would learn and go seek those if given a tiny bit of guidance. Tons of non-technical people have learned to get their hands on playable guitar tabs the same way.

As for the playing interface, I like it quite a bit. Plenty of people will comment about how anything getting in the way of becoming an expert in sight reading is somehow evil (hyperbole) but this is silly. I could easily recommend this app to friends who played Guitar Hero as kids and now want to play along to stuff on the piano or keyboard– hey, we all got older and maybe acquired more "mature" instruments with black and white keys. I used to read standard sheet music for chamber/orchestra but it's been years and frankly it's the least important skill for the type of music that I play. However I do have a piano and once in a while want to play something without getting into a lesson on sheet music especially since what I used to read had far less range than a piano.

App Store note: searching for "piano tabs" the app doesn't show up even after a lot of scrolling. "piano tabs learning & practice" finds it as the top result. I am a fan of the plain name; it's short and self-explanatory to the point that I imagine people do randomly search those terms without knowing about your app. That should be a good thing but in practice it seems the discoverability isn't there which is worth looking into.