Apollo is a great app; I think people like it so much because Christian has always been so engaged with the user community and has (mostly) been responsive to people. I don’t know if I’d go so far as to call it a work of art, and I don’t necessarily agree with all of the monetization limitations that were built in to it, but it is unquestionably one of the apps I’ve used the most over the years and it will be sorely missed.