Señas de identidad is the inauguration of what Goytisolo himself refers to as his ‘mature period’. It is the first instalment of the Mendiola trilogy and the first fruit of the major existential crisis, the ‘desgarradora labor de autocrítica—política, literaria, personal’ (D, 343), which the author underwent in 1963.

Critics have been quick to stress that Señas is a transitional work, and Goytisolo himself frequently points out that it contains the flaws and imperfections of its author's search for a new mode of writing. He compares it to Tiempo de silencio, ‘una obra aún vacilante, desnivelada y con bastantes aristas […] el comienzo de una nueva etapa’ (D, 165). For this reason one must guard against the tendency to treat Señas as an aesthetically accomplished work. Indeed a large part of its interest and subversive effect, as we will see, is due to its imperfection, for it reveals the situation of an author in crisis. Its uneven texture, narrative dislocations and ambiguities are the signs of the author's attempt to break free of a restrictive tradition.

Señas, and even subsequent novels, tends to be interpreted in terms of realism. Most critics point to the importance of language and form. José Ortega notes how in Señas ‘predomina todavía el referente o realidad social, pero el motivo o significado va cediendo al significante o lenguaje, y el personaje […] va transformando la aventura moral […] en aventura lingüística’. Ortega sees Alvaro as alienated and setting about substituting history with a new mythology in which the relationship of language to reality is put in question. Carlos Fuentes also stresses that the focal point of Señas and subsequent novels is on language, seen as the root of experience and the site of ideological control.

Critics, then, often treat Señas in one of two ways: either the innovatory form serves the interests of greater realism, or form and content parallel each other, Alvaro's dilemma and critique of Spain constituting an implicit attack on the ideological appropriation of language.

There is, however, a much more radical project at work in Señas. Even at this early stage the principles of Structuralism and Russian Formalism were starting to make their mark on the author's work.