Currently, there is a lack of empirically validated usability evaluation methods that can properly be integrated during the early stages of Web development processes. This has motivated us to propose a usability inspection method called WUEP that can be integrated into different model-driven Web development processes. In previous work, we presented the operationalization and validation of WUEP in a specific process based on the Object-Oriented Hypermedia (OO-H) method. In this paper, we present further analysis of the empirical validation of the operationalization of WUEP into WebML, which is one of the most well-known industrial model-driven Web development process. The effectiveness, efficiency, perceived ease of use, and satisfaction of WUEP was evaluated in comparison to Heuristic Evaluation. The results show that WUEP is more effective and efficient than heuristic evaluation in the detection of usability problems. The inspectors were also satisfied when applying WUEP, and found it easier to use than heuristic evaluation.