Jenkins practices what it preaches. Minor version number releases occur about once a week. New features appear, bugs are resolved, and new bugs introduced. In general, the great majority of changes lead to improvement, but a few do not. However, when introduced, bugs are generally caught early and removed quickly.
Before updating Jenkins for new features and potential stability glitches, it's worth reading the changelog (http://jenkins-ci.org/changelog). Occasionally, you might want to speed up a deployment to production because of a security issue or miss a version due to a stability blooper.