We also use New Relic and are extremely pleased with it. However if we agree that all 5 of the OP's points are legitimate identifiers of a well-rounded monitoring system, New Relic only meets 3 of the 5: deep integration, high resolution, and dynamic configuration.

New Relic is indeed an excellent monitoring tool but it's not perfect. Alerts do lag behind anywhere from two to 5 minutes, and there are no context-sensitive alerts... at least not that I'm aware of.