The only issue I've had is with the keyboard occasionally disappearing in the middle of typing a comment. now if you happen to be attempting to play any of zynga's games that is a totally different story. Seems they still are not forthcoming on how a flash based game crashes on a flash enabled tablet and have no intention of addressing that issue by either an fix or an app. (but they sure love kissing up to i-platforms and droids ) All the other fb "toys" work great bridged or wifi (though video can be touchy)
I am so sick of the FB devs changing the site I just use the app on my tablet and phone anyway!
And as you play on FaceBook you can be certain Mark Zuckerberg is laying next to you watching every keystroke or swipe. If anyone must use FaceBook, I recommend enabling Private Browsing mode on the BlackBerry PlayBook.
I don't use FB much but the site has never crashed my browser. Seems the max number of tabs I can have up without popping off the browser is ~8 depending on how "busy" they are. BTW, I have my privacy set fairly high on FB.