There should be a demo site with fake data.
Screen shots are nice, but to set up the app and then discover it's not for you, is a hassle.
Thomas Homolka commented
@mattermost.org The two links for the demo don't seem to work anymore. Would be great you get your feedback on that. On behalf of my company i would be interessted to see a demo.
We have two demo sites:
1. https://demo.mattermost.com: open source, Team Edition server on the latest Mattermost release
2. https://pre-release.mattermost.com: Enterprise Edition server, which is a pre-view instance of Mattermost built daily with latest changes from the master branch: https://github.com/mattermost/platform