Updated:

You can report bugs, give feedback or suggestion either here in the comment section or on GitHub.

If you just want to play around you can use the sandbox.

Overveiw

Basic Features
•    WYSIWYG focused (no markdown)
•    Embedding of HTML syntax
•    Unlimited page revisions
•    Recent changes
•    Colored side by side diff support
•    Uploading and embedding of images via drag & drop
•    Automatic highlighting of broken interwiki links
•    Content can be categorized in namespaces
•    Extended Access Control Lists
•    Nested commenting
•    Activity feed
•    Fast full text search by algolia
High Usability
•    Easy navigation through breadcrumbs
•    Embedding of Content
•    Automatic update of interwiki links
•    Templating system
•    Table of Contents widget
•    Youtube integration
•    Footnote widget