The CodeDeploy service seems to operate by you manually launching base ec2 instance with a code deploy agent and then this agent will checkout your git code on the live instance, run any provisioning steps and then if things break somehow rollback all that work, still on the live instance.
I'm sure this is still a big improvement to companies who are manually sshing into servers and running deployments by hand, but as someone who pre-bakes ami's and does rolling upgrades with autoscaling groups this service seems like a step backwards.