I have bought room cooler a month ago from Rawalpindi. Its 32 inch by 32 inch in size. Made up of 24 gauge steel sheet, plus the motors have copper winding and have 5 year warranty. Although it drinks a lot of water like 4 buckets after every 4 hours but it is very effective in Rawalpindi/Islamabad (at least before monsoon). When its working you can touch its base, its just like water from a fridge. The water circulation makes the water and air cool.
I also have an exhaust fan in my room which throws the hot air outside, hence an air passage is formed, cool air is getting in due to air cooler and at the end of the room, hot air is getting out due to exhaust fan.
As far as power consumption is concerned, the shopkeeper told me that it is equal to two ceiling fans as the room cooler has two motors, one for spinning the fan and other for the water pump.