I have taken several Pre-workout supplements, including C4, Assault, 1MR, Jack3D (original), and NO-Explode.
Many people report incredible results upon using Craze. I used Craze having been off pre-workout supplements for several months, and I definitely noticed the effects during the first workout.
In terms of Concentration/Focus, I was able to completely block out my surroundings and plow through my workout. In terms of strength, I did not make any significant gains on any single exercise, but instead was able to put up high weight for all the exercises in my workout across the board.
I work out after work, and usually I am pretty exhausted at that point (9-5PM). Craze delivered more than enough energy to get me through my workout and keep me awake for several hours afterwards. I had no problem sleeping at night, due to the exhaustion from both work and the high intensity workout.
Craze would be a good choice for anybody on a cut, as my appetite was noticeably suppressed post-workout. It does not do much for the "pump", but people have reported stacking with Hemavol for great results.
For people who are new to preworkouts, Craze is a great choice. It is a very consistent product, with a reputable brand and ingredient profile. For people who are familiar with preworkouts, Craze will most likely be equivalent to, or better than any preworkouts you have used in the past. I cannot name a single product that delivered better results, although Assault and Jack3D were probably just as good.
Over time you will develop a tolerance, so I would suggest using it sparingly. Otherwise, Craze is a great product that mixes well, tastes great, and provides consistent results.