High5 IsoGel is not really a gel at all. Despite the name, it's a liquid. So it's a carb-based sports drink in a gel-style sachet. Thus, it delivers energy and hydration - unlike normal gels where you need to take on liquid separately - but it's of questionable benefit for most road cyclists.
Each sachet of IsoGel is 60g. According to the packaging, each gel contains 26g of carbohydrate, providing 104 kcal of energy. According to the High5 website, each gel contains 22g of carb, providing 88 kcal.
Either way, the main ingredients include water, glucose and fruit juice. The texture is - as you might expect - just like watered-down fruit juice. The taste is not sweet at all, making this drink very pleasant and refreshing.