it's pleasant, pleasing and worth for the struggle to reach there on hill -top spend a few nights, smell the aroma ( not the bad smell of city slum) take a mornig stroll and just keep walking till you are tired. For a short stay ooty is the BEST. I had gone several times to Kodai, but somehow ooty has its own charm. you will feel the difference once you are in both places and I am not wrong once you climb ooty hills. People who have enough time must take train to reach there and you will really enjoy the journey. best timing will be september as peak summer is crowded and possibility of pollution and take care in hotels - you can't escape from food-poisoning. July and sugust are bad times with monsoon rains and sometimes landslides- so avoind taking risk of going those times.