I really like Carthage's architecture, but there are two things I don't like about it.
1. You can't edit the frameworks unless you open a separate project, re-edit and recompile. With Pods, you can edit the Pod in your workspace.
2. Carthage doesn't go the last mile to bundle the framework into your project.
If they addressed those two things, I feel like Cocoapods would probably start losing a lot of steam. Although, after watching some videos about what the goals of Carthage were from the creators, I doubt that those two things will be addressed so I'm waiting for Swift's Package Manager.
I consider both points a feature. I think the Xcode project of the dependency should be a black box, I just want to get the resulting framework to add to my workspace.