The article explores the relationship between the functional potential of metaphor and the expression and perception of the author’s opinion. Metaphor is considered as a means of implicit speech impact exerted both from the positions of its generation and perception. This paper aims to identify the correlation between the author’s opinion and various aspects of metaphor power, namely density (the number of metaphors per text), intensity (the ratio of new and conventional metaphors) and the metaphor projections typology (the ratio among orientational, ontological, and structural metaphors). The data for the study were obtained from a two-stage linguistic experiment. First, 20 experts in Russian Philology and Journalism composed three-part texts about Russia (its history, culture, and people), and were asked to summarise their personal opinion in the most relevant part. Then 180 respondents who were students of Moscow State Linguistics University identified the author’s position in the composed essays. The latter were analysed using metaphor-driven discourse analysis (MDDA), which included the identification of metaphor density, their intensity, and functional typology indices. Next, the MDDA numerical values of indices were juxtaposed with the data reflecting the author’s opinion expression and its perception by the respondents. The findings showed that metaphor intensity and density are related to the verbal message persuasion, since in 80% of the cases personal opinion was set forth in those text parts that contained the greatest number of the author’s metaphors. The proven relationship between metaphor power and the author’s opinion expression makes it possible to identify metaphorical speech impact, which reflects forms and degrees of speech impact in different types of texts. Thus, the results expand the theoretical and practical framework for the study of metaphorical speech persuasion.