Good response to current transients (during rapid charge/discharge
cycles when PLL is locking). Compare PLL settling times if a
X7R capacitor is used in a loop filter : slower settling than with
film..
Capacitance vs. Temperature change is small like C0G.
Piezo-electric effect is low : lower spurious due to vibration than
when using a ceramic capacitor.
Downside is that the film-capacitors are not quite as robust as
ceramic ones : melt easily if touched with a soldering iron !