When using git-flow the killer feature is that you can configure it to automatically deploy feature branches to internal testers, the develop branch to an external group, and master to the real App/Play stores. All upon commit. Super duper.
I use it every day, compared to self-managed Jenkins it makes all my tasks way faster and easier. It is also great way to provide a better overview of the process to partners and clients.
great product with great integrations e.g. Slack or Relution