New Relic: Our Review...
Ever since we used New Relic's APM product to track down a long running performance issue on an Ecommerce site we have been very impressed with New Relic's suite of monitoring applications. As a ‘full landscape’ monitoring solution we would always recommend Paesslers comprehensive PRTG solution, however if you need more detailed monitoring coverage of key applications and user behaviour, New Relic is the best option as a powerful, entirely application focused supplement.
Traditional landscape monitoring will tend to give you the ‘what’ whereas New Relic gives you the ‘why’.
For large deployments – you need to know both.