I count any writer as "good" if he or she can hold my attention and make me give a shit about the people in the books and what happens to them.

So often I find writers that people gush about as being "great writers" fail in that. Yes, the language is pretty - but neither the plot or the people interest me - and often the write is trying too hard to be a pretentious prick. TS Elliot is a prime example of this. Every time I find a used copy of The Once and Future King, I buy it and rip it up and throw it away so some poor bastard doesn't try to read the damn thing. I figure it's an act of literary charity.