The similarity problem is one of the most famous open problems in the theory of C * -algebras. We say that a C * -algebra A satisfies the similarity property ((SP) for short) if every bounded homomorphism u : A → B(H) is similar to a * -homomorphism and that a von Neumann algebra A satisfies the weak similarity property ((WSP) for short) if every w * -conitnuous unital and bounded homomorphism u : A → B(H), where H is a Hilbert space, is similar to a * -homomorphism. We prove that a von Neumann algebra A satisfies (WSP) if and only if the algebras A ′ ⊗B(ℓ 2 (I)) are hyperreflexive for all cardinals I. In the case in which A is a separably acting von Neumann algebra we prove that it satisfies (WSP) if and only if the algebra A ′ ⊗B(ℓ 2 (N)) is hyperreflexive. We also introduce the hypothesis (CHH): Every hyperreflexive separably acting von Neumann algebra is completely hyperreflexive. We show that under (CHH), all C * -algebras satisfy (SP). Finally, we prove that the spatial tensor product A ⊗B, where A is an injective von Neumann algebra and B is a von Neumann algebra satisfying (WSP), also satisfies (WSP) and we provide an upper bound for the w * -similarity degree d * (A ⊗B).