Meet the acceptance criteria, don't exceed it

During the initial sprint reviews for our current project it became apparent that the team weren't meeting the acceptance criteria for the user stories that made up the Sprint Backlog.

Our retrospectives helped us find that this was generally because the team over-built, delivering more functionality than was actually required to meet the stories.

The team felt that they were doing the right thing in delivering more to the Product Owner, however as they were pushing themselves to deliver a higher volume of functionality they lost sight on delivering high quality software ultimately meaning that we were failing our client by delivering an unusable, buggy system.

This also affected our Product Owner as the additional functionality had not been previously approved by them.  If additional work was going to be delivered our Product Owner should have the authority to determine what that functionality should be.

When discussed with the team they realised the impacts that this was having and agreed to do only what was in the stories.