Wow! People here are childish.
Here's my take on it:
1) People who boast about their great social life(on the Internet

) and how FB sucks and they don't use it and all, I'm happy for you and your lifestyle.
So please continue with that lifestyle and don't post about it again and again.
There are people , like me, who uses Facebook so this news is relevant for us.
2) I'm using iMessage, Whatsapp and Facebook Messenger.
And there are advantage of FB messenger which no other service provider has.
If it's not obvious here it is:
Cross platform : You don't need to be on any particular device to use this.
I can chat with my friend who is on using PC using my iPhone.
No other platform has this simplicity.
iMessage is only for Apple devices and you can't have use Whatsapp on PC.
You can even chat with someone who doesn't have a smartphone.
3) Facebook home: I think I'm not alone in saying that but it's crap.
Like many people I've installed it, tried it out for 10 mins and uninstalled it.
4) Chatheads: This is one thing FB did right. In the hindsight, I'm shocked how no other messaging service did it first.
Chatheads on Android: This is how it should be. Perfect implementation.
No chatheads are not that stickers or big emotions.
It is just a minimized chat.
Here's how it is useful. I was just reading an article today and one of my friend messaged me.
Instead of getting a notification I got a chathead. I saw his message and replied. Tapped on the chathead and it minimized. Till the time he was replying , I kept on doing what I was doing.
It's 100 times more easier than having to switch between apps.
If anyone says it's useless, then honestly you haven't used it.
It is for this feature alone I would tell my friends to message me on FB instead of Whatsapp , because its a intuitive way of messaging.
Chatheads on iOS, from what I've seen is just useless. It's like taking a shower wearing raincoat.
If I'm inside the app already what's the point of chat heads.
I really wish Apple does something about it( I know they won't) because having a conversation with someone on iPad while doing what I was doing is just the way it should be.