I'm having a serious argument with a friend on the status of the word "suck" when I used it about him by saying "You suck!" because he missed a train. We are both non-native English speakers. He claimed that I used it as a foul or slang term. I vehemently disagreed with him about it. I told him that the word "suck" can be used to describe something inefficient or not good enough as well like it is used in the example "Samsung mobile sucks". 

Am I right to describe the use of the word "suck" in such context?