It offers high-performance, great security features and a modular design. While it started as a regular syslogd, rsyslog has evolved into a kind of swiss army knife of logging, being able to accept inputs from a wide variety of sources, transform them, and output to the results to diverse destinations.
It can deliver over one million messages per second to local destinations when limited processing is applied (based on v7, December 2013). Even with remote destinations and more elaborate processing the performance is usually considered “stunning”.
It has a strong enterprise focus but also scales down to small systems. It supports, among others, MySQL, PostgreSQL, failover log destinations, ElasticSearch, syslog/tcp transport, fine grain output format control, high precision timestamps, queued operations and the ability to filter on any message part.