Undoubtedly, foreign language teaching intends to make students obtain the required competence so as to get the linguistic knowledge needed in a foreign language. With this respect, a textbook should supply to the users as much as possible, be satisfactory to fit into the syllabus, and meet all the needs and expectations of the students during the learning process in order to achieve required targets in foreign language learning. Particularly in English Language Teaching, textbooks as the basic instructional materials are expected to build learners' four skills that are speaking, listening, reading and writing. Depending on this basic assumption, this study attempts to get in-depth evaluation of the textbook in terms of methodology and language content, language skills, practicality, topic, social and cultural values by taking into consideration university first year students and their instructors' evaluations, observations, beliefs, and suggestions on the textbook. From the students' perspectives, results reveal that the textbook is moderately efficient in terms of methodology and language content, language skills, practicality, topic, social and cultural values; however, instructors find some parts of the textbook weak; especially some aspects of language skills, practicality, social and cultural values. As a result, the textbook is neither completely insufficient nor perfectly adequate. At the end of the study some suggestions for instructors and material writers are provided.