If generating leads and collecting email addresses is important to you then read on.
Up to now I have always advocated targeting people via Facebook but when you get their attention get 
them off of Facebook and onto your site asap. Once on your site look to get their email address by use of an opt in form.
The rise in mobile use has actually been a bit problematic for this strategy. While the surge in mobile Facebook use has allowed you to target people quickly and cheaply it is not that easy to fill out an opt in form on a mobile. Due to this conversions on mobile can actually be more expensive than on a desktop even if the actual traffic is cheaper.
Facebook clearly would like to keep people on Facebook as long as possible and help you more conversions with your mobile traffic.
Well Facebook is now offering what are called Lead Ads, This is where you can get people to subscribe for something directly in their newsfeed and Facebook will pre-populate the form for you with the details they used when signing up to Facebook. If all you want is name and email well then the form will be completely filled in.
This could be a game changer but questions still remain. As of now you can’t directly connect Facebook opt in form directly to a CRM or email marketing system such as Aweber, you need to download a csv file from Facebook and then upload into your CRM etc. This is very manual and slow and we know on-line people expect thing fast.
It is been rolled out for mobile first but desktop is coming.
I am going to promote my 5 steps report as an offer to test these lead ads , I will let you know how I get on.