How come Tung Che Hua could be considered a failure?
Tung Chee Hwa wanted to resolve the housing problems in HK and already had a plan in place to do it. However, Asian financial crisis and SARS had basically destroyed the housing market. He was forced to soften and abandon his housing policies.
Donald Tsang who succeeded Tung ended all public housing projects and colluded with property tycoons which gave rise to one of the most expensive housing market in the world. If Tung Chee Hwa were a strong leader, he would not step down and housing prices would not go to the roof.
In addition, Tung Chee Hwa is a good person but maybe too good a person that he isn't a good politician. Tung has allowed his subordinates to have free hands in many policies.
A few of those policies that enacted by then would become a major problem later on. First, Tung allowed schools to end require study of China, modern China, and modern China history and replace it with liberal studies which is a disaster. Instead of helping young students to understand China, liberal studies classes have become a major platform to teach anti-China and anti-Chinese idea.
Tung Chee Hwa allowed a new law to protect environment which limit reclamation of shoreline for housing, protection of park, forest, from further development, much longer public consultation period for any infrastructure projects. At first these policies make sense. However, these environmental policies were weaponized by the property tycoons and environmental groups that prevent the HK government to find lands for public housing or development.
Tung Chee Hwa made many concessions to public servants, professionals that later these groups become very powerful and influential. For example, Hong Kong doesn't allow any doctors and nurses from other countries to practice in HK even though there are major shortages of such people due to the Medical association has the power to regulate such matter. These kinds of special interest groups are so common in HK that average Hong Kongers were forced to endure low quality of services and expensive fees which bred resentment.