Sensu is an Infrastructure and monitoring / telemetry solution. There are big sites using it such as Yahoo, Yelp, Cisco, and Tesla.
Sensu provides standard solutions for monitoring and alerting.Which I can say is okay. However If you have been following my Telemetry and Microservices blog posts series(part1 and part2) you will see sensu is not ideal for other use cases like:
* Dynamic Thresholds / ML
* Infrastructure Tracking
Because Sensu it doesn't have a Time Series database. You can use Sensu with Graphite or InfluxDB to work around it. However IMHO the solution it would be: have collectors(collectd) to get basic HOST metrics plus app instrumentation and them make checkers that do queries over the TSDB.