Reddit.com: Can We Revive php.net User Notes Or Kill It?
The question, however, has always been "how useful is this feature really and does it bring more harm than good?". It's not that easy to answer since there are so many notes submitted by a wide range of users and some will likely go unnoticed while others seem to get undue attention due to their positioning near the top of the user-notes section of a particularly trafficked page.
The poster proposes a few things that could help make them a bit more effective (and useful overall) including voting on the note contents, flagging potential issues and sorting the notes based on popularity/age. He's put together a proof of concept as seen here with some of the new features.