The SimpliSafe system works very well but it is a shame that you need to pay for active monitoring to get app alerts on your phone if the sensors detect something. No cost for having the SimpliSafe indoor camera send alerts but entry sensors and the like require a subscription.
Similar systems from the likes of Ring or Eufy don’t seem to charge anything for app usage (arming/disarming system, alerts) but SimpliSafe seem set to continue with their current charging scheme.