Gosh, how many of you have actually used Facebook Home? "I saw a YouTube video once" simply doesn't count. The fact that it's on Android appears to be the biggest problem in this thread.
Anyway, I installed it on my S3 yesterday, and it's pretty cool. I'm not a big user of Facebook - I mean that, I haven't set a status for over a year now - but I like to get involved with it. It's a very nice Lockscreen - the app tray admittedly leaves much to be desired.
ChatHeads are absolutely undeniably useful, and dare I say it, somewhat innovative. Sure, quick reply SMS hacks have been around for years - but nothing as refined as this. I've changed my default SMS app to Facebook Messenger - something iOS doesn't allow for - and it works great. All my contacts have photos, thanks to OS X, so I'm ticking over nicely here. Multi-tasking, great looking messaging - Facebook messages and SMS in one app too.
Those of you slating it should consider the "choice" option that has previously been argued in this thread. Sure, it might not be for you, but for up to 1 billion others (# active Facebook users) - it might well be. For the majority of consumers, the option to have high-quality, interactive images of their friends (in real-time) on their Lockscreen/Homescreen is going to be tempting. Apple are going to want to counter that temptation.
PS. For those of you saying it's all about Facebook...it's definitely not. The only Facebook thing is your interactive background - the rest works as a standard Launcher, with some extra data tracking going on. You can even have your regular Lockscreen if you want, using Home as the unlocked Homescreen.