Application insights is an AMAZING tool for monitoring your application. Using the Microsoft.ApplicationInsights.TraceListener
package with
Microsoft.AspNet.WebApi.Tracing
captures a great deal of information automatically which has reduced my time to identify bugs dramatically.
The Analytics dashboard allows for quick and easy slicing and dicing of data collected. I recently needed to see all Error Traces and found it to be somewhat indirect. I was expecting severityLevel to be 'Error', but it was an integer. Looking at the TraceLevel enum, Error = 1 so maybe that would match. Nope. Error is 3. I imagine this matches something, but it was not obvious so here is how you can get all error traces in the last 24 hours:
// Find error traces in the past 24 hours
traces
| where timestamp > ago(24h) and severityLevel == 3
