I cannot really think of any new words that have entered the culture from Facebook. There are some new ways of using old words, such as using “friend” as a verb or using “like” to refer to the process of clicking the “like” button. These are neither negative nor positive. They are just part of the natural process of language change.
While we may think that our language is meant to be the way it is right now (or the way it was when we were younger), there is no reason why a language should remain in a certain state. Language naturally changes over time as our circumstances change. Language also changes in fairly random ways as words come to be used differently for no apparent reason.
When word usage changes, we often think that it is bad because we think our language is somehow becoming degraded. However, this is simply not so. The way we use words is neither bad nor good. It is simply a type of fashion. Therefore, the ways in which Facebook has affected our use of words are neither good nor bad.