It is really easy in Icinga to create your own plugin and integrate it without any fuss. And it works just perfectly fine.
Icinga offers automatic service restarts, high stability, and supports various add-ons for flexible monitoring. It allows custom plugin creation and integration, providing extensive customization through scripting and querying. However, installation and configuration are complex, and remote monitoring can be frustrating. Support is not very responsive, the automation needs improvement, and it lacks advanced dashboard creation capabilities.