It could help if you already have a large dedicated following. But not to build one from scratch unless you are really clever.
Facebook is on its way out as an advertising medium IMO anyway, it has changed the updates feed recently such that only about 15% of your fans will see your posts, you have to PAY to have them all see your posts now. But that isn't economical for a local band, not even close.
You really won't attract many new fans though with FB ad campaigns unless you are a genius and tie it in with a lot of other coordinated local PR
, people just don't look at those unless you really do something brilliant and even then you are quickly forgotten.
The math for gig advertising or exposure is really ugly. If you target your local area and demographics and get a 2% click rate and about 1% of those shows up, which is good, you are going to need to advertise to 500,000 Facebookers to get 100 people in the door. That likely won't be economical for you or even possible.
It can work to help your image if you are well known already, but even then your money is far better spent on other advertising such as bribing the media and prominent local bloggers to pump you up.