Twitter works on 2 levels.
The first is complete and utter garbage posted by mindless Z list watchers with nothing better to do with their time - Good luck to them but it's not for me.
The other level is great for getting information out to people quickly. WBC, Mersey Travel,Merseyside Police, Met Office (to name but a few) all have Twitter accounts and tweet regarding local issues.
Another way of using it is, for instance, you hear of a news event breaking either nationally or internationally - use that as your search word and you'll get instant info from people that are there in the thick of it.