Before I bought Field I watched several reviews and in none of them the Hold “sequencer” made any sense. Literally everyone missed its main feature. When you hold any keys and either rotate grey knob counter-clockwise or press shift + <, the keys will be held transposed down into the “hold” range. This way you can build a multi-octave key combinations and then transpose them up and down the range. (Hard to explain in text, but try it and you will immediately see what I mean.)
One thing I think is missing is the ability to transpose the combination off the keyboard or out of “hold” range. If this was possible (as an option, at least) you could continuously morph the sound without ever stopping it it. That would be pretty awesome for ambient compositions.