Looking for Feedback on Readups, a new social reading tool

Hi Everyone,

I'm looking for some feedback on a new tool we just built for reading online together, (computer and ipad in a web browser), called ReadUps. We've seen some teachers using it but I'd like to know what you think, or how it could be improved. Thanks!

http://www.readups.com

About ReadUps:

ReadUps (http://www.readups.com) is a social reading site where people can “meet up” inside what they read. We think about it like a book group inside a book. How it works: a teacher fills in a few textboxes to create a ReadUp, adds content (epub ebook / pasted text / imported URL), picks a timeframe, and invites people via Twitter. The book lives at a URL until the expiration date hits, then the ReadUp disappears. During the ReadUp, content is social in two ways: shared comments and responses on paragraphs and real-time messaging for people reading at the same time. We think it's useful for contextual book discussion, as well as for online critiques of student writing projects.

Thanks!

Travis