Evaluated it and a couple of others. Chose Bosun, never looked back, it's probably the only system with flexible and concise DSL for evaluating alerts (somewhat similar to R in spirit).
We evaluated both Bosun and Riemann for our use case and chose Riemann. Use case is over 10,000 servers with over 2 million metrics incoming every XX seconds. Riemann simply performs better, probably because it uses streams instead of a poller. The other part of our use case is to use it primarily for alerting, and it's fantastically responsive and robust for that, including simple integration with other systems (email, Slack, nagios, PagerDuty, etc). Bosun seems like a good tool for other uses however.
How do you know actually? A lot changed in past 4-5 years, having a soldier with a black eye is a whole lot of trouble for commanding officers and they sometimes take ridiculous measures to prevent that. Of course it's not same everywhere, but it's army after all.
People should at least try to see forest behind trees. It's not only cows or only almonds. The reason land dies is very complex one, mostly because ecosystems become unbalanced through abuse by CAFO and unsustainable farming.
Riemann rocks, just not as monitoring system.
Bosun link: http://bosun.org/