I just set it up last week to push data to Graphite. It took a little bit of time to understand how to configure it and the docs have conflicting information in some places. Also, you will need to build it yourself or get a PPA if you're on Ubuntu 12.04 and want to use it with Graphite since the version that Ubuntu ships with doesn't support graphite.
I haven't tried to write plugins for it but it comes with a lot out of the box and it's working well.
I haven't tried to write plugins for it but it comes with a lot out of the box and it's working well.