In the opening section of the novel, Nick rather derisively discusses the idea that in his college years he was often "privy to the secret griefs of wild, unknown men". He goes on to say that he has grown impatient with hoping that people will prove themselves to be good at heart, despite appearances to the contrary.
This is all said as a lead-in to the introduction of Gatsby.
Nick says that Gatsby is the one exception to his impatience. Though Nick says, "Gatsby represented everything for which I have unaffected scorn" he also uses the words "gorgeous" and "all right" to describe Gatsby, commenting on the truly impressive capacity for hope in Gatsby.
This description is ambiguous indeed. From this brief introduction we understand that Gatsby will 1) offer "secret griefs" to Nick and Nick probably will not want to hear them, 2) Nick will come to admire Gatsby, and 3) despite this admiration, Gatsby still qualifies as a "wild" man in this passage and represents many things that Nick abhors.
Admiring this figure is like admiring a monster. This, at least, is the conclusion available to us after reading the opening section of the novel. For the most part this interpretation is borne out by the narrative as Nick at turns detests and applauds Gatsby as a man who is admirable only despite his deep flaws (but this admiration is not diminished by the flaws and may be enhanced by them in a strange and unique way).