It is a breeze to setup and will import all of your friends' birthday's once you sign into Facebook through the app. What I like most about it is that it will notify you via the notification system letting you know if there is a birthday coming up. On top of that, you can post from within the Birthdays app to Facebook without having to open Facebook so that is a huge plus too. You can also add widgets to your homescreen too.
There are ads with the Free version which is expected, but a pro version is available for $2.99.
If you no longer want to miss out on your friend's birthday and would like to post on their Facebook wall give the Birthdays app a try.
Review:
+ Free version available w/plenty of features
+ Easy to use/import Facebook contacts
+ Notifications implemented
+ Post to Facebook within the Birthdays app
- Ads w/free version
- Interface is a bit bland
- Pro version doesn't offer much more
- Notification icon is slightly off
Google Play Store Link