Well, using DataDog I can 1) increase a counter when something happens -- like an error or an expected user action and 2) setup an alert when the average amount

Well, using DataDog I can 1) increase a counter when something happens -- like an error or an expected user action and 2) setup an alert when the average amount of events over a X minute period is sustained above or below a certain threshold -- with a separate trigger per e.g. host. So more than 60 error in a 5-minute period, or a sustained 10mbps for more than few minutes triggers, and sends me an email with a nice embedded graph. Compared to all the other DD features -- like dashboards with all the metrics that can also be, to some limited degree, shared, Anomalous seems kind of limited at a glance. DD is $15/host/month.