It's an opportunity to break with Pawn and use something more efficient and easier language to write plugins.
It brings the possibility to extend with almost everything you can imagine (as you can extend eg. node.js, which is also based on V8 ).
Also, availibility to reload a script in real time, in the a middle of a map.
With some investment, it can be added to hook HLDS engine functions not provided by plugin api, etc.
My fantasy is very limited, but i think this community has unlimited ideas for this