He's added some features over time -- one of the most requested was a meditation timer, and so the iPad app comes with an option for background noise, as well as a timer that will stop or even put the iPad to sleep whenever you want. DeVoe's also put a few of his own little touches in the app: if you look closely at the screen while tilting it around, you'll see the shadows underneath the objects move with the accelerometer, a very subtle effect that you'll only notice if you look for it.
DeVoe has played around with prices quite a bit since his app hit the store one day one way back when. He's been as high as US$7.99, and as low as $3.99 (which is where the iPhone version is currently set), and he decided to put the iPad app at $5.99. He doesn't want to go much lower than that -- at 99 cents, he says, there's more money to be made, but there's almost a stigma against pricing so low, as if a 99 cent app is somehow worth less, even if it's well-made. Plus, he told me, "at 99 cents you lose money until you hit the top 50."
There are also lite versions available, with fewer objects to see, and none of the meditation timer functionality. iZen Garden is a cool metaphor app that does what it says on the box, and in the end, DeVoe says, that's what most of his users want. The App Store, for him, is a direct connection between "my customers and me."