Whilst the potential of online Computer Assisted Language Learning (CALL) in terms of access, immediacy and exposure is widely acknowledged, as yet remarkably little is known about its impact on the user population, be they language teachers or learners. Indeed, beyond its technological development, online CALL design is still affected by a dearth of reliable evaluative data, critically needed for improving the interface design, implementation and integration. On this premise, this paper proposes to focus on a range of appropriate evaluation methods applied to a recently authored web-based interactive CALL interface, comprising multimedia interactive exercises and self testing, as part of an ongoing research combining Human Computer Interaction (HCI), Java programming and language teaching expertise. This current evaluation adopts a novel approach insofar as its main objectives are not only to assess the usability and usefulness of the interface as well as the student experience, but also to compare the different methods used on the basis of their input and evaluative output. Ultimately, this paper will strive to bring theory and practice closer together by shedding further light on the crucial role of evaluation, the appropriateness of the data it generates and its applicability to online CALL development.