His problem is that he concludes that the world is in a better shape than many people want to believe -- and usually people stop reading here and get mad, instead of following him through. In addition to that, he thinks that in many ways, we are doing the right thing in our efforts. For some problems, he suggests more efficient solutions, however.
If you want to read his answers to some of the more serious criticisms:
And if you want to know what some people think that oppose his views (at least in parts), visit their site: