Don't use it to the exclusion of external tools though. monit doesn't help if the server has no connectivity or no power. On a similar tangent, configuring a mutual restart policy (eg: if cron fails monit restarts it and vice versa) is also a good idea.
Actually automatic countermeasures are almost always a bad idea. Don't do it.
If a service crashes repeatedly then fix the service, don't deploy bandaids. Those bandaids tend to pile up and god help you when that pile comes crashing down...
