I wouldn't touch energy drinks with a 10 foot pole but I'll break down the contents of this particular can for you (see pic) note that each can is two servings
Sugars - 54 grams per can. That is about 13.5 teaspoons of sugar, which is about 200 calories. So all of your calories are coming from pure sugar. This is twice what you would get in a can of Coke Classic
Riboflavin, Niacin, Vit. B6 and B12 - you should be getting these things from a healthy diet anyways.
Sodium 0.36 grams - surprisingly this is not that much sodium. This is about half the sodium you'll find in a tbsp of soy sauce. This is about the same as a can of Coke Classic, which is still high.
The sugar and sodium is almost twice the content of an equivalent volume of Gatorade.
Taurine - 2 grams This is a compound found in many energy drinks. 7 grams a day of Taurine is considered non-GRAS so you ok considering nothing else in your diet is pumping your body filled with taurine. Taurine has not been shown to give energy, but it MAY be linked to decreasing muscle fatigue. The study is here if you want to read it.
U. Warskulat, U. Flogel, C. Jacoby, H.-G. Hartwig, M. Thewissen, M. W. Merx, A. Molojavyi, B. Heller-Stilb, J. Schrader and D. Haussinger (2004). "Taurine transporter knockout depletes muscle taurine levels and results in severe skeletal muscle impairment but leaves cardiac function uncompromised". FASEB J.: 03-0496fje. DOI:10.1096/fj.03-0496fje
Panax Ginseng - 0.4 grams
This was taken from wikipediaOne of Panax ginseng's most common side-effects is the inability to sleep. Other side-effects include nausea, diarrhea, euphoria, headaches, epistaxis, high blood pressure, low blood pressure, mastalgia, and vaginal bleeding
The common adaptogen ginsengs (Panax ginseng and Panax quinquefolia) are generally considered to be relatively safe even in large amounts.
Panax ginseng is not recommended within Chinese Medicine to be administered along with anti-infective herbs unless a person is quite debilitated, because of the fear that the pathogen will be tonified. Herbalists in China believed this and according to Xu Dachun in his brief essay on ginseng (1757 A.D., during the Qing Dynasty): "if one administers Ginseng of a purely supplementing nature, then one will merely supplement the evil influences and help them settle down. In minor cases, the evil influences will, as a result of such mistaken therapy, never leave the body again. In serious cases, death is inevitable
Energy blend (including Caffeine) - 5 grams
I'm not sure how much caffeine is in their blend, but I am sure it is a lot because they list it as a blend and not individually. Caffeine has a half life of 3-4 hours in your body (which means that half of it is metabolozed every 3-4 hours) and is a diuretic (meaning that it makes you urinate, thus lose water).
Read more on caffeine here
I am not going to write much more since I have a load of information here, but I will say that taking in that much sugar spikes your insulin levels and not only will you crash afterwards, but it doesn't help your body burn fat.
Basically I stick to either water (for regular workouts) or a 50:50 mixture of water and gatorade for long runs (over 2 hours long).