Easily configurable for project granularity. For example, I can define the relevant git repository's branch to a build project/job, provide the necessary build tasks with lots of different executables and scripts, and segregate the build from the release stage with parallel jobs for only specific users or groups. Lots of popular language integrations with multiple notification methods and great integration with other Atlassian products.
Free only for first 7 days (as of June 25, 2015), although for only $10/mo for 10 jobs for 1 remote agent, it's a solid option for those ready to use enterprise-ready tools like Bamboo and its brothers and sisters of Atlassian products. I hope that there becomes a greater focus for mobile applications.
For enterprise ready Continuous Integration tool, Bamboo is a great choice paired with other Atlassian products.
Fast and contiguous partitioning of build and deployment tasks. Bamboo is a chiefly a continuous integration tool, but it does great in assisting with deployment issues and segregating build tasks to allow you to debug your code. Automated merging of branches is also a great feature.