What version of Koha are we up to?
Prosentient's policy is to remain a version behind the latest because this gives time for the majority of bugs to be ironed out.
Koha is a large application with many interacting parts and a change in one area can have subtle effects which may take time to surface. We find that our clients prefer stability over interruptions to their business, even if this means waiting a bit longer for the latest feature.
Bug fixes and new features in Koha are documented in Release Notes at the time a new version becomes available and these can be found on the Koha Community Wiki or by Googling koha release notes.