I did this last fall(at least the first half) until I redeployed to where I had no access to a gym. I did this program along with my regular lifting routine, and made great gains in strength(and decent gains in muscle).
When I maxed out at the end of the first mesocycle, I realized that I had underestimated my beginning 1RM. Definitely test your 1RM before you start, or you won’t get the full benefit of the program.
At the end of the 4-week mesocycle, I maxed out at 445. Using that to calculate the second half(which I was able to perform about the first week or so of the second mesocycle), I found out really quick how low I had been on the first part.
I’m talking legs so sore it felt like I was ripping muscle from the bone just standing out of a chair.
As I said, I did it in conjunction with my normal lifting routine, and was pushing poundages on all lifts(totally clean, BTW). However, I was lucky enough to be in a position where all I did was eat, sleep and lift. I had no strenuous work to do, which I have no doubt helped immensely with my recovery.
If you are not in this type of situation, then you would definitely want to back off on your other lifting. I would still hit all the major muscle groups, but dial down the intensity a few notches on those, to a maintenance level.
The program WORKS. I would recommend a casein protein supplement for bedtime, just to aid with recovery.