Theres no need to register account and provide your email or name. You just need to be signed in your iCloud account.
All the data is backed up by iCloud and only you have access to it. Everything is automatically synced across all your devices.
You can create your workouts and exercises, check your previous workouts, look at your progress with visual graphs.
Gymblebee uses HealthKit API. With your permission, workouts will be saved into Apples Activity app. Watch app will also ask your permission to access HealthKit data to show your Heart BPM.