The alerts are very useful, they let me know when my site goes down for any reason.
Sometimes it takes them quite some time to get around to sending out an alert, but that's not too bad as long as I'm aware of what's going on with my server! It would be nice if there was more flexibility in how you can set up your own rules, such as allowing multiple domains or IP addresses to have their downtime monitored by one account rather than having all of them go through separate accounts. We use Wormly because we need to monitor our websites so that we're always informed whenever something happens. If our sites were ever unavailable, this gives us peace of mind knowing that someone will be notified immediately and hopefully fix whatever issue caused the downtime.