Broken chords - also known as arpeggios - are very useful for building quick comps for slow, ballad-type songs. In this video tutorial I look at how to put them together and some of the problems you might run into.
The beauty of broken chords comps is that, at their simplest, you don't have to worry too much about creating a complex improvisation, because you can restrict yourself to just playing the notes of the chords. You do, however, have to remember that precision is really important, especially if you're new to the piano. Broken chords quickly sound very sloppy if you make mistakes - and, because the fingering can be awkward and you can have big stretches to deal with, mistakes are quite easy to make.
The basic message about broken chords on the piano is that they're very easy in principle, but can be awkward in practice!
I also say a couple of things about how to use your piano's sustain pedal with broken chords - especially if you're swapping between digital and acoustic pianos, when there can be variations in the amount of sympathetic resonance you experience.