I had a difficult time understanding the value/functions of this as well. Is it a browser plugin? Does it utilize my address book to autofill contacts? Do my friends need to download the application as well in order for me to send them things? Can I copy/paste files with it?

Sure, I'm kind of playing the dumb user here - but it did take me about a minute to figure all of that out, which is probably more than most people would spend. For me, the most helpful page was in the Chrome Web Store where there were screenshots - that made everything click.