Assessment is a compulsory semantic component of the speech genre of a scientific review. The evaluative nature of the scientific review along with its dependence on norms of science-based ethics determines the significance of such category as assertiveness for the speech genre. Assertiveness is defined as expressed by linguistic and non-linguistic means and characterized by extra-linguistic conditionality, as a semantic-pragmatic category of statement, having a modus nature and correlated with the process of demonstrating the degree of speaker's confidence and peremptoriness to the conveyed information. A positive assessment in scientific reviews accepts both indirect and direct ways of expression and is substantially free of ethical taboos, whereas a negative assessment needs implications which allow softening the position of a reviewer. The article looks into lexical and semantic means of indirectly expressed negative assessment typical of scientific reviews.