The most valuable features are the flexibility, ease of use for writing new test cases, the test plans, and the composition.
TestRail is highly valued for its stability, flexibility, and ease of use in writing test cases, including test plans and compositions. It excels in management features for testing processes, reporting, and evidence documentation, with robust Jira integration. Users appreciate its various test case templates and test artifact maintenance. However, improvements are needed in custom reporting, usability, traceability, API integration with Jenkins, and pricing.