As with every release, the KMyMoney development team continues to work hard to make each version better and easier to use in every way. This is the third release in the 5.1 series, and most of the activity has been directed to fixing bugs.
As of 5.1, the conversion to using KDE Frameworks™ is essentially complete, although that and the work to update many of the underlying libraries used by the application are behind the scenes and not directly visible to the end user. The general look and feel should be stable, although some minor changes may still occur. The basic functionality of the program also remains the same, aside from intentional improvements and additions.
In past releases, this page of the manual has included a list of many of the specific bug fixes and functional enhancements. However, rather than duplicating that information, you can find it directly in the Changelog.
Since the release of 5.0, there have been some changes which will need adjustments on the user's side if you are upgrading from 4.8.x or an older version. However, we expect that most users have converted to 5.x by now.
For some time now, the program searches for the templates for the printcheck plugin in different locations than previously. If this is still an issue for you, you need to account for this in the plugins setting dialog, see this section for more details.