Looks like the plan is to expand it to terrorism and escaped prisoners amongst other things so in answer to the original question - Do I want to be woken up at 4am to be warned to avoid a town I am close to and might be going to? Yes. But it may not be what they use it for at the moment...
Good grief. So you think they wouldn't use it in the event of a terrorist attack because they didn't list it on their website? What a strange hill to choose to die on. At least we won't get alert about it, I suppose.