It worked for me until I reached my 50's, then it's an injury waiting to happen and 100% will for older lifters. One of my biggest challenges is having to choose between "heavy duty" (which has always worked well beyond other methods for my body) and certain injury (100% with high intensity, heavy, low rep approach even with enough rest once the lifter hits 50). I have chosen to change my approach to avoid injury which means I now use higher rep, lower weight, moderate intensity methods just short of failure. It works, albeit not as effectively as heavy duty training, at least for me. But its better than being injured...
As an aside, I have always believed that Mentzer's approach works best for endomorph and mesomorph body types, who gain mass and strength easily but struggle more with cuts (like myself).