This product works well. You will not feel a rush of energy, but rather a steady, even level of energy.
In addition, Hammer gel flavors, at least the ones I've tried,orange,tropical and raspberry are not terribly sweet. Lastly, even though this is not important to some, it may be to others, these are vegan products.
A good deal if you grab some hammer gel flasks, and can handle refilling your own flasks. There are rumors that if you are on the trails in forest park, you might see a wild eyed man with very short hair downing a whole bottle of the espresso flavor.
I bought the "nocciola" flavor, which is great if you like Nutella. It doesn't taste overly sweet, and sits well on my stomach. My wife likes it, too--amazing, given that she can't handle any food or drink before long runs. The large bottle is more economical and environmentally friendly than single-serve packets. Opened bottles don't need refrigeration if you consume all the gel within two months.
I've been using hammer gel for many years. Moreso when I was younger and riding 60* miles at a pop. In summation this is great for a boost on a longer ride to prevent bonking. Now my rides are only 1.5 hours and this is all I have before the ride. I have always used the flavors containing caffeine. Hammer gel has quality ingredients without surplus sugar.
I use gels for nutrition on longer rides in place of more solids as I have digesting the solids. The Hammer product provides the calories and electrolytes that I need. Buying in bulk and using the hammer reusable bottle saves a great deal of money and helps protect the environment by eliminating the foil packet trash.
The downsides to the combo 1) the bottle has a protective cap and a VERY tight pop top makoing it difficult to use while in motion and 2) the last few servings are a little more difficult to get out of the reuseable bottle. This is overcome by adding a bit of drink from your water bottle prior to starting out making more of a liquidized gel.
I've been using Hammer Nutrition Gel for an energy source for all my rides from a quick hill training ride to 24-hour rides. I use it along with Hammer's Perpetuem and electrolytes in my water as a constant source of energy throughout the ride. It's easy to digest this way. I don't like having to swallow the gel straight and then wash it down, but this approach provides the benefit without the gag. And the variety of flavors keeps things from getting boring.
I prefer to fuel on whole foods when riding, homemade rice bars etc. When I ride, this gel is in a 5 shot flask in my jersey pocket. Gel packets are sticky trash in my jersey or accidently dropped on the road. I mix flavors fo Hammer Gel in a flask or on their own. Easy to use, dose how you need it. Great for that emergency to avoid the bonk. Not a big fan as using this as only fuel, more of needing a quick blast to get over the next climb or long stretch of fast tempo. I always have a flask in my swim bag or in my jersey, period. I've been a Hammer Gel fan for over 15 years.