We investigate the impact that general concept inclusions and role-value maps have on the complexity and decidability of reasoning in the description logic . On the one hand, we give a more direct proof for ExpTime-hardness of subsumption w.r.t. general concept inclusions in . On the other hand, we determine restrictions on role-value maps that ensure decidability of subsumption, but we also show undecidability for the cases where these restrictions are not satisfied.