Datadog has shit the bed for us multiple times in the last six months. Unannounced breaking API changes, unaddressed bugs, and now their embedded cert expired.
Our org is currently divided over further commitment to the service, or leaving them entirely. They've made it very hard to argue in their favor.
Their pricing doesn't scale well either, IMO. We have several hundred hosts running and for some of the smaller instance types it costs just as much to monitor than it does to run the entire machine.
Datadog failed, and our WAF provider failed at the same time too (internal services). It was .. rather confusing at it seemed like the sky was falling D: .
Thanks for mentioning this, since it caused me to go check metrics and find they weren't coming in... Luckily only a couple of my alarms come from metrics via the agent itself.
Found it ironic that the top of their page advertises "Security Monitoring now available".