1. It supercharges your Joomla site with functionality we've always dreamt of (nested categories, author profiles, tagging, comments, sharing features, auto-sized images etc).
2. It's damn easy for the users to get used to - we've used it for several sites now, and it's rare that the end users putting the content in ever need to come back to us for more training or assistance.
Get to know K2 and you'll grow to love your Joomla all over again.