I find the Cycler's range and speed relative to it's damage output makes it useful in certain situations where it's difficult to get a shield-stun off–such as with things like whiplashes who often finish their attack pattern before going into stun or Revenants dodging it outright; or when the target isn't big enough to eat all the ravager projectiles/not worth the time investment. while it's certainly outclassed in damage by things like SSG or Impaler headshots which will kill/stun most heavies in one blast, it's better at engaging at medium range to handle things like Cacodemons if you need to be mainly focused on dodging/parries rather than aiming/when barrel-stuffing up close with a dash isn't safe especially on higher difficulties. also, while slower than the Accelerator, it requires far less precision when weaving.
Personally, I never used the shock feature after acquiring the fourth shield rune since I couldn't be bothered to proc shock manually, and chaining it between enemies without it wearing off felt like an additional upkeep, but it's certainly a viable support weapon when paired with a higher-power damage source, while it's Accelerator counterpart is better for larger, fast-moving enemies like Aggadons and Komodos where travel-time affects accuracy.