You might also want to look at Go[1] from ThoughtWorks* - the UI and first class Pipeline support is it +ves.

[1] - http://www.thoughtworks.com/products/go-continuous-delivery/...

* - I work for ThoughtWorks, but not associated with the Go team, and use Teamcity and Jenkins more than Go.

Superior? Depends on what you're building. Using TeamCity to set up builds for iOS is a royal pain in the ass, and their OS X support in general is greatly lacking. I've had to create a whole ecosystem of shell scripts just to produce signed .ipa builds for QA -- which is kinda the point of purchasing a licence to a CI system to begin with.

is it free?