The Electricity supply in Dubai is very well organized. Even if there is a problem in power supply every now and then, they would efficiently solve the problem within minutes to ensure the citizens uninterrupted power supply.
There were only a couple of times that the power was cut longer than a hour or so, owing to some critical technical problems. As far as I remember, the biggest power cut took place was on June 9, 2005. It took them several hours to resolve the problem. Needless to say, people had to face a lot of problems. The other two major power cuts took place in 1999 (because of a major generator failure) and recently on April 28, 2008 in Al Safa area respectively, which were resolved in less than an hour.
It is quite good if the system works that well at this place.The thing of concern is the fact that this place is so very hot most of the year, and the power cuts can drive you nuts.
Their electricity lines are much better because they run the lines underground. This makes the cities look a lot cleaner but makes maintenance for electricity lines very difficult as you have to do it underground. A lot of times this can cause problems for the workers, but its better overall as it is much cleaner.