The new rendition of Awakening Ninja's Sura ChaoSpree adds a slow-motion effect to the game that creates a large amount of desynchronization.
This is pretty bad, because it stops the skill from being used reliably in PvE and PvP.

Additionally, Black Spirit's Rage iteration of the skill declares a -50% movement speed on targets, but does not actually debuff the target with this. The -15 DP debuff works, but that's it.

New Information has been revealed.
The -50% movement slow debuff for 5 seconds is completely overriden by the -10% movement slow for 10 seconds of a skill add-on applied to the skill.
If you run the movement slow debuff skill add-on, the -50% movement slow debuff will never come into effect.

The slow-motion special visual effect that desynchs the game is still there.