I was really happy with this one. Most products with similar claims don't come close to delivering. I started using it about a month into my summer cut and the best thing I noticed was muscle denisty and hardening that I hadn't had in past cuts. Improved sleep certainly helped with recovery and I felt better throughout each workout. Seemed to kick in pretty quick too. Libido was better after about day 4-5, Sleep was better after just 2-3 days. I think the price is also very reasonable as its much less than other products that don't work as well.