From what I've seen, not really. GitHub.app saves you from needing to know what staging, push, pull, fetch are. If you're already productive with Tower then I think going to GitHub.app would be like putting the training wheels back on.
which would you recommend for a designer to use as an intro to Git and source control in general? I'm trying to get my partner into git to collaborate with me. Is this client still just as easy when using it on a non github repo? or is its integration with github its main drawcard?
I recommend Tower for designers, and SourceTree for developers. The github client has nice integration with github, but it is not as well-designed as Tower and not as powerful and workflow-efficient as SourceTree, IMO.