I can go back and look at the menus again, but my experience is that "What's New" is just a quick tutorial of BD-Live functionality - like how to do "My Scenes", "My Chat", etc.
The other items you're referencing are part of the BD-Live menu screen. The community element allows you to log in to the Universal system and send messages to other people online or watch the movie with them. The content center is a collection of trailers for other Universal product, occasionally mixed with live events or chats with the filmmakers. As I understand it, Judd Apatow did a live chat, but I haven't looked at the Blu-ray since I submitted the review.
As for an opinion about these functions, I've found the "What's New" switch to be useful for anyone who has never watched a blu-ray before, but redundant for anyone who has. The other functions are just typical BD-Live items that are useful for people who want to make use out of them. For me, I haven't had a movie I wanted to watch online while chatting, and the amount of useful downloads I've found has been a bit limited. Occasionally, I'll find additional featurettes online (such as with Coraline), but the trailers are usually the kind of thing I can already find on the disc or somewhere else convenient.