it's an iOS app, so it should work on iphone/ipad/ipod (I think?) https://itunes.apple.com/au/app/atar-notes/id611598677?mt=8
Just going to extend on to what laseredd has just said and that it's made for iPod/iPhone usage due to the fact where you have at the bottom right hand side a magnification button to increase the overall size of the app itself (since it was made for those smaller devices). Having said that, it does work but you don't get the 'Latest' forum posts on the main screen but rather all the main-boards on the main page. Alongside there's a Notes section and the Atar Calculator on the side bar which is good to use but other than that it's a really simple app but a good one