The best thing about centeon is that it's open-source software which means you have access to everything, including the documentation and community support for your product.
If there are any issues at all with Centeon, or if there is anything specific in your implementation of the system that isn't working as expected, then they can help you fix it without charge! There really aren't many cons other than perhaps being able to do certain things ourselves (i.e., set up an alert) but this is something we'd need to consult our Account Manager about anyway. We've been using Centeon since 2015 for data acquisition from our various cloud applications such as Salesforce, Slack, and more. It has allowed us to automate processes so much easier than before, while also providing better analytics and insight into what exactly went wrong during those events.