It's easy to setup/manage and deploy across all your environments with it being web based which makes deployments very simple.
For us as administrators we need to be able to set custom alerts for our own use but that could do without some of the more complex functions like creating graphs or even better reporting features. We just wanted something that was robust and reliable at a low cost so this does those things well. Having access via web browser works really well too - no client side install needed.