Well, I already started a thread on this but to answer the question, yes, he will be good. The real question is when. Before the season I thought he was 2 years away. As of right now I think I was right - he was 2 years away or a year and a half away right now. I just hope he hits enough so we don't trade our future away for a centerfielder.
I also think he is not ready yet for the big show. Over the winter, I wanted the Yanks to grab a guy for 2 years. During ST, I wanted them to get a guy for next season only, after Bernie leaves. I think Melky would have been perfect for Spring Training 2007, to be annointed the starter, at age 22.
But, he's here now. He will strenghten CF defensively, and will contribute at least whatever Womack was, except for all the SBs. But is his bat ready? I am not convinced, although the early signs in AAA were very positive.