why does he have mixed feeling toward thecburmese people?

The narrator actually thinks the British should leave Burma. He feels the hostility of the local people. He understands why they do not want to be occupied. He has trouble dealing with their hostility of the natives,

When a nimble Burman tripped me up on the football field and the referee (another Burman) looked the other way, the crowd yelled with hideous laughter. This happened more than once. In the end the sneering yellow faces of young men that met me everywhere, the insults hooted after me when I was at a safe distance, got badly on my nerves.