The idea behind this build is to semi spec around the cleave ability and add burst damage to your person while cloaked. Basically you appear, do major damage and blink. I will go ahead and say that this build may not be better than the standard auto attack/blink based Zeratul builds but it does have legs in its own way. This build is merely a different approach to a good hero. That's all.

By the time you hit 16 with this build you will be at a point where you initiating from cloak mode:

1) Deals gradual damage over time
2) Gives you a noticeable damage boost to your auto attack damage for 5 seconds
3) Deals additional damage with the cleave as your opening attack
4) Does all of the above on multiple targets

It becomes a lot to deal with especially when you have good teammates following up on your decisions.