In languages like java, OOP is often used as a hack to make up for lack of language functionality. The result is very boilerplate-looking code. However that does not mean that OOP itself is worthless. CLOS in my opinion provides you with oop in the shape of a handy tool, with a focus on what the compiler can do to make your life easier rather than philosophical issues. Even just for that I think it's worth taking a look at. Things that perplex c++ and java programmers for years, like the visitor design pattern, become obvious once you learn what double dispatching is through CLOS