If something is noteworthy, it is important or interesting enough that you should stop and give it your attention. It is a quieter word than famous or great: a noteworthy fact might never make the news, but it is still worth putting in your notes. You meet it in news, school writing, and careful talk — a noteworthy change, a noteworthy performance, it is noteworthy that… Teachers and journalists like it because it points without shouting. Though actually, people also use it as a polite lift or a soft warning: calling a small success noteworthy can be kind, and calling a problem noteworthy can mean “do not skip this”. It is not kitchen-table talk; many speakers would just say worth noticing or interesting. It usually describes things, events, and facts more than people (a notable person is the more usual pair). The feeling is “this deserves a look”, not “this is the biggest thing in the world”.