When Google Fit first came out, it was little more than a step counter, but now it's stepping up its game. You can now track your runs, and plug into third-party apps that track things like sleep and nutrition.
The new updates make Google Fit ideal as a top-down look at your health, particularly if you're already using other services. On the nutrition side, integration with MyFitnessPal, Fatsecret, Lifesum, and LoseIt are expected to rollout in the coming days. There are also several sleep-tracking apps that will integrate with Google Fit.
If you happen to use an Android Wear device (which are kinda useful sometimes!), the new version of the app can also detect when you're doing sit-ups, push-ups, and squats and track this activity as well. That way, you don't have to manually enter that information.