Strudel (and his brother Tidal Cycles) is mainly a live coding tool for events like Algorave and similar. The changes can be re-evaluated in real time without disrupting the timing and flow. Everything is patternable (not only notes, but also effect parameters, chords, volume..).
Upside: very fast prototyping of macro structures, cyclic patterns and basic arrangements. Fast iteration, faster than moving around or cut/paste lots of identical bars in piano roll.
Downside: every unique detail (non-looping melodies, particular dynamic variations) must be typed out and timed properly (script gets longer). In that respect, a piano roll approach is faster.
This tool is constantly evolving, though, many obstacles will be hopefully removed.