What are some alternatives?
When comparing Slack Metabot and Missions, you can also consider the following products
Slack Gitsin - A beautiful Slack command line interface
PullReminders - Review and release pull requests faster with Slack reminders and metrics.
slackcat - Post command line output directly to Slack.
Shlack - Whoa, a bash shell inside Slack!
Wey - Fast open source Slack desktop app