A midi controller which allows you to create your own custom layouts. My first impression was a very clear UI, very easy to use, very well thought out... And I have to say that it is also my last impression. I will just add a few things... The App is really steady. You have a big choice of modules organised in 9 categories. Each of them comes with its own setting menu. Note that it is the only Midi Controller which comes with a dedicated music sheet module! Note that to use this module, you will have to import a PDF file into S1MidiTrigger by using iTunes File Sharing or the Open in feature. Something that I also really like in this App, is that you can align objects on the Grid, Group them, Copy them with their settings... Another great feature is the SnapShots... Let me explain: A layout is my "Studio Set Up". For example, I have created a setup for controlling a Virtual Synthesizer (a Keyboard & a X / Y Pad). A Transport (to control a Virtual Drum Machine or Sequencer) and a Score Module to display my Tab. This is my Set Up and I use it everyday, for a lot of Songs. So, for each Song I will be able (with just a Tap) to save a SnapShot, to create a Set List and to share it via email or iTunes File Sharing. I really love this App, so without any hesitation, I will rate it as a Killer App!