We do a lot more than linting. Code Climate finds complexity and duplication issues as well, and turns that into clear, timely feedback for the developers. For example, if you introduce some new duplication (perhaps you intended to refactor but got sidetracked), Code Climate can let you know as soon as the code reaches GitHub, so you can resolve it right away (or not -- depending on the situation).

Linting is a very small part of what we do. If you're already using JSHint locally as a pre-commit hook, it's probably not better than that. (We'll pickup and automatically use your JSHint config in that case.) We added linting because in our experience a lot of projects with JS (especially Rails apps) don't use linting, and we wanted to expose the value of linting to those people in a zero-effort way.