This question, posed of Mary Shelley's Frankenstein, brings about two very different answers. Essentially, either answer's basis comes about by each individual reader and his or her own personal ideologies regarding what makes a human being a human being.
First, if one believes a human being to be one which looks human, acts human, and possesses language, one could only deem the Creature a man. Given the Creature's desire for companionship, his mastery and eloquence of language, and physical likeness to a human being, the Creature is a man. He reasons; he speaks with compassion, and he desires the same things most men do: companionship and love.
On the other hand, if one believes that a man can only be a man if he possesses a soul, then the argument could be made that the Creature is not a man. Given that Victor was only able to give the creature the physical characteristics of a man, and not "insert" a soul, one could very easily state that the Creature fails to be truly human. This said, one could also argue that the Creature does seem to possess a soul--given his desire for all things human.
Therefore, the defining of the Creature's being is a personal one. Does the physicality of the Creature make him human, or does the lack of a true soul make him something else?