I personally find this to be underwhelming.

Facebook, a company/service that integrates photos, events, videos, music, books, web apps, and integrates your social circle into all of that, releases what is almost their own OS that only encompasses the news feed and messages.
Where's the contacts integration? Facebook photos and videos in the gallery? Events in the calendar? Like button in the browser or on music, books and movies? (Also does this thing support widgets? Live wallpapers?)
What about the app center? Since I have to sign in to use this, why not display my Facebook apps in the app drawer alongside my Android apps?

Well, there's always room for improvement and Facebook said they'll be updating this every month so we might see them quiet my complaints before you know it.

(Source: Business Insider)