Yes, check out the online demo to see how awesome Piwik is!
Please note that while this demo is useful to see what Piwik has to offer, it does not show all features. Indeed, the administration area is password protected. If you download and install Piwik yourself (or use a Hosting partner), you will get access to many more interesting features and reports.

If you prefer seeing the list of features all in one page, check out the list of features.