I did not get the certification but I reviewed the course and exam for ACE several years ago. (all courses are reviewed before they grant CEUs). I found it worth taking; if you knew the material the exam was reasonable. If you are going to be dealing with athletes it is a good starting specialty certification after you get your basic one.
I ontained this certification years ago in my Master’s program. It is a must-have certification, especially paired up with NSCA-CSCS. The exam was difficult and you have to study hard for it, but you will learn a lot and it is well worth it! You will learn new skills that you not only appy to athletes, but all populations.