The 30 days trial for ThingWorx Analytics does indeed opened the interactive API guide.
This UI allows you to execute REST call to ThingWorx Analytics as you would do with any other REST client hence providing the same functionality.
Regarding the ThingWorx Analytics extension, they are indeed accessible to entitled customers only.
However you can trial the extension if you start a 30 days Trail for ThingWorx in the dashboard (in addition to the ThingWorx Analytics).
the Analytics extension is provided in this ThingWorx trial, simply open the mashup TW.Analytics.ConsoleMainMashup