We didn’t find it plain sailing getting up to speed with all of the packages. Although many users barely look at user documentation, preferring to learn by using the software, with one of our packages you might find that approach tough going, and with another you’d be pretty much guaranteed to fail. User documentation and other sources of support are, therefore, not just the icing on the cake.
LibreOffice Impress is well catered for. There’s a Getting Started Guide and a Base Guide for the LibreOffice suite as a whole and an Impress Guide, even though the latter is pegged at version 4.2. Beyond this, there’s lots of community support including online help and mailing lists. For Calligra Stage there is an Introductory Handbook for the Calligra suite and a Stage Handbook but they’re not as up to date as the LibreOffice user guides, both being dated 2012. There’s also a general Calligra forum.