To measure the success of a user onboarding process in a GUI, consider the following metrics:

1. Completion rate: Percentage of users completing the onboarding process.

2. Time-to-completion: Time taken to complete the onboarding process.

3. Drop-off points: Identify where users abandon the onboarding process.

4. User satisfaction: Collect feedback through surveys or ratings.

5. Net Promoter Score (NPS): Measure user loyalty and satisfaction.

6. Feature adoption: Track usage of key features and functionality.

7. Retention rate: Measure user retention over time.

8. Support requests: Monitor decrease in support requests related to onboarding.

9. User engagement: Track user activity, such as logins, sessions, and interactions.

10. Conversion rate: Measure achievement of desired outcomes (e.g., completing a task).

11. Learning curve: Assess user understanding and mastery of the GUI.

12. User confidence: Evaluate user confidence in using the GUI.

13. Onboarding duration: Measure the time spent on onboarding.

14. Bounce rate: Track users who leave the GUI during onboarding.

15. Return on Investment (ROI): Calculate the ROI of onboarding efforts.

By tracking these metrics, you can evaluate the effectiveness of your user onboarding process, identify areas for improvement, and make data-driven decisions to optimize the experience.