It's funny you mention BVA. I joined them many years ago (before FSX closed gamespy) and I flew with them quite a bit. I think I was just a little intimidated by how professional they were. I did a few of their lessons, and then I went back to free flight in the offline sim where I could take off the from the taxi ways :).
This is a lot of fun. I've always been a huge fan of flight sims, but I never realized that ATC was just as much fun.
Just a few notes:
* All the planes enter at 90 degree angles. I assume this is intentional, but it would be nice to have semi-random entry angles.
* There are a fixed number of planes in the simulation. It would be more challenging and fun if more planes would arrive while I'm taking care of the others.
* The words are small and hard to read.
All in all I think this is a really cool simulation. I can see myself wasting many more hours on it. Thanks!
Another possible metric for rating apps could simply be how many users use an app on a consistent basis and how many hours they've logged in the app. If you get an app that has 5 negative reviews and 1 positive review, but you have over 100 people using it everyday for a few hours it should be rated highly regardless of the negative reviews.
That would let you access your data forever, albeit you might still need to write your own scripts to port it to another app.