I have used the grandfather of this application when it was called Microsoft Operation Manager (MOM). It can be annoying, sending out alerts after another for the most mundane to weird situations. eg DAC component out of date, high memory usage. etc
It is however really useful to tell you the health of your applications, eg mail queues of Exchange Server, long running jobs of SQL servers. etc
That is if you can get it to work.
I was looking at the monthly availability reports from SCOM and noticed that my SQL Cluster virtual servers are not showing up. After some googling found a most astonishing fact. SCOM 2007 will only recognize the first virtual server. You have to implement an override for clusters.