I would agree with George on the sainthood aspect of this topic. But fwiw, I would also add (as far as his actual writings go) that some caution is necessary. He had a tendency to exaggerate, or make claims based on very little evidence, if he thought that the argument would benefit his cause. This is typical of many apologists, and Justin was no different just because he had the word "Saint" added centuries later. For example, Justin made the absurd claim that Christians "marry only to produce children" (First Apology, 29), so as to make Christians look like moral people. Of course, most early Fathers, and even the Bible, would disagree with such a statement, but Justin's object was not to provide a treatise on Orthodoxy, it was simply to make Christiniaty look acceptable to people with certain biases (perhaps stoic, given these types of arguments). Anyway, I would suggest just reading through
his writings, and then deciding what you think about him, rather than letting me (or anyone else) persuade you one way or the other.