Sure there is. Primarily the requirement to have a runtime installed followed secondarily by the fact that many of the useful features are encapsulated in Apple specific libraries (or NeXT Step, although GNUStep takes care of that on many platforms).

Every other complaint I have against the language just stems from my familiarity with C++ and love of static typing (or compiler hints and syntactic niceties useful for writing high performance code - namely games).

Because there is no class library that is multi-platform and integrates somewhat nicely into the platform. Yes, I know GNUStep, but it doesn't come close to e.g. Qt in terms of integration.