I like the particle effect, but wonder if it might look better if it appeared at the location of the block being destroyed. Where it is now, it makes it hard to see what you're shooting (though maybe that's the intent).
Also, this could use mouse sensitivity adjustment. In Chrome on OSX the slightest mouse movement caused me to spin around many times.
@DaleP, yeah, Unity is pretty sensitive when it comes to the standard character controller. Unfortunately, it is also barebones to controlling how sensitive it is. (I think there is some amount of customization, but, I could never get it to work. :/)
Also, this could use mouse sensitivity adjustment. In Chrome on OSX the slightest mouse movement caused me to spin around many times.