Ergo Proxy is an adult story that puts your head to think about several topics, including the existence of the man and his relation with god and the machine. All this stuff is presented in a dark and futuristic ambient and you could find a lot of philosophical theories too.
Its excelent animation, a fantastic ost and the adorable characters complete an amazing work that will keeps you expectant in front of the tv until the end.
So, if you like to think and interpret aspects about life you'll have to give it a try. Otherwise, if you are looking for simple things and no complications get away from it.