Thumbtack's mobile onboarding flow is streamlined, allowing users to create an account and initiate a project in under 7 minutes with clear actions on each screen. However, the process has some drawbacks, including a lack of information leading to user confusion, inability to edit submissions, and a significant anxiety from submitting a project without previewing it. Overall, the onboarding experience is intuitive with effective design, but it could benefit from improvements to reduce user anxiety and enhance functionality.