It's very effective. I'd highly recommend it. It can also be easily merged with other intermediate programs.
The only thing I would suggest is to not get too caught up in the progression on Monday and Friday thing. Starting out of course the goal should be progression on both but as long as you are progressing on Monday and not REgressing on Friday you'll see great results. Those are good guidelines that MR gives of course on how to gauge the interplay between MON and FRI but it can be very difficult to predict since things can change so much based on outside things. Certainly just because you don't get a new PR on one Friday you wouldn't want to change Monday. And even a regression can turn out to be temporary. With this kind of training you need to be patient, that's for sure.
Friday's workout, for the most part, is about reinforcing the gains made on Monday. What you do on Friday is really not enought, in itself, to result in a whole lot of new fitness. If it were the volume would be too high and this would be a different program
In general progress on Monday and try for PR's on Friday but don't expect them one hundred percent of the time. Give it time and if you see a complete lack of progression on Friday for a good period then consider changing Monday. That's really the same thing MR says of course but the way he puts it I think may lead people to overemphasize and thus overdo Friday. It should tend toward progression but Monday progress is the main point.