I like parallel mode of deployment. I like reliability of the service. Also You don't need to read a lot of documentation to start working with it. And the most valuable feature for me it is parallel deployment to many nodes that saves time.

Support for build and SSH command, multiple servers, atomic deployments, REST API.

DeployHQ makes it simple to move files from a repository to the webservers at a click of a button. I used to drag and drop the files by FTP; now once it's set up, you select your commit and hit deploy! Also comes with zero downtime, which is awesome.