I don't see anything here, with the exception of the debounce decorator, that isn't just an excuse to use a decorator for some reason. All of the examples can be implemented without decorators with the same amount of complexity and clarity.
That's what I thought, and there are lodash & underscore to do twenty different flavours of debounce.
However, stuff like @killEvent and @stopPropagation does make sense.
The great thing about React is that it's easy to reason about. Devs new to React can quickly come up to speed. When you start decorating React components like this, you're introducing magic and making React code less easy to reason about. I'm not saying that you should avoid this in all cases, but you should consider the pros and cons and be careful. It seems that decorators at the component class level provide a mechanism to bring back mixins for those who want to use ES6 React components with mixins.
Decorating individual functions probably isn't a bad thing in those cases. The link takes you to only part of the Github repo. Look at the rest of it and you will see various class-level decorators.
To play Devil's advocate, function composition can accomplish literally anything that's conputable, and principle of least power would suggest that having specific and limited syntax for common patterns is productive.
If Javascript continues to admit statement-based syntax, I think decorators are appropriate, because they allow the functional decorator pattern to be applied to function (and method, and class) declarations.
It is also worth noting that the decorator syntax is still not final, and using it with Babel 6 requires https://github.com/loganfsmyth/babel-plugin-transform-decora.... More details on the decorator deprecation is in that repo.