The new site is still in the beta stage, so it's not totally perfect at the moment. And you may at first be frustrated with the number of big titles currently missing from the collection. For example, I used AFI's list of 100 greatest movie quotes to see just how thorough MovieClips is, and I was disappointed that many in the top ten, including bits from Gone With the Wind, Sudden Impact and Cool Hand Luke, are as yet unavailable.
Those three movies would be perfect for one of the site's main purposes, expressing your mood via a movie quote on Facebook. Admittedly, I'd like to share Network's "I'm mad as hell, and I'm not going to take this anymore!" on a regular basis. Unfortunately, MovieClips doesn't have it. My guess, though, is that the collection of clips will continue to grow and eventually we'll all be able to communicate through movie dialogue, much in the way the aliens do in Explorers (another film not currently represented on MovieClips).
For now, there's still a lot of fun to be had browsing through the many scenes that are available on the site. Here's a clip from Poltergeist II: The Other Side, for instance, that should get a lot of play on the pages of fearful kids about to get fitted with braces. (Related, MovieClips also has the part from Parenthood when Kevin loses his retainer). Will this sort of thing make adolescent emoting more enjoyable? All I can say is I wish I had MovieClips (and, well, the internet) when I was a teen, to cinematically communicate what high school felt like to me: