In a nutshell, jkim is right.
Sugar is a simple carb and metabolised in a process known as "glucose metabolism", which is basically how quickly your body can deliver glucose into the bloodstream.
The primary reason for limiting your sugar is to minimise the risk of reduced insulin sensitivity which can result Type 2 diabetes. Reading up a bit on it, the WHO recommends that sugars (including those found in fruit, honey, juice etc.) should not account for more than 10% of the energy intake of a healthy diet, with carbs in total being 55%-75%. Presumably, the rest of your intake should be protein and fats.
The brain runs on the energy it gets from blood glucose in your body. So if you don't have enough in your blood, you'll suffer physically and mentally. You need some glucose, but not too much of it. Per 100ml of Gatorade it's 0.5g of glucose and 5.5g of sucrose. Sucrose is table sugar, which is made up of glucose and fructose. Sucrose is also a macronutrient which will give a rapid rise in your blood glucose levels. Hence, when drinking something akin to Gatorade, your energy levels will get a quick burst. It is not, however, part of a balanced diet. It's also 4 calories to 1g carb. So if you're carb intake is 399 grams for instance -it's 4 x 399 = 1596cal. 10% of 1596 is 159.
So a bottle of Gatorade is probably going to max out your sugar intake for the day. Eating an orange or another fruit is probably a safer bet really. Having the odd Gatorade isn't going to damage your health as much as a can of Coke will. And I say that on the basis that Coke contains a much higher sugar content.
>> I dont know about froma fitness point of view, but when i played football and soccer as a kid i always felt "better" when drinking gatorade as opposed to water.<<
Drinking water is the safer bet. But in terms of it giving you more energy, Gatorade beats water hands down. The only reason it will hydrate you quicker is simply because it tastes nice and you'll drink more of it more quickly than water. I guess this is my justification for drinking it when doing a lot of running. But I usuall only have it if I haven't had much water during the day or if I am really, really tired and need a boost.