Media galleries are slide shows. There is a summary page with a listing of all galleries and preview of their slides. Clicking on the preview opens a full size view of the slide as pop up. The summary page cannot be configured. Clicking a media gallery shows a larger, configurable grid of slides. Clicking on a slide either shows a strangely small pop-up view of the slide or large view of the slide in a new page (configurable).
Images can be uploaded one by one. There is no bulk upload option. It is quite time consuming to upload a slide show. Powerpoints or odps cannot be uploaded or shown. Videos can be uploaded up to a size of 6 MB but cannot be played. They are just downloadable.