Best of them all. I've tried several apps that play z-file games and this is by far the most intuitive and user friendly interpreter by a long shot. I'm not going to mark it down for not being able to handle glulx files because even now there are none that can. Twisty claims to be able to  but it doesn't work for me  at least not with the game I've tried anyway. This is a definite keeper. Very  very highly recommended.
January 13 2016