For those that don't have the top genetics (we've all seen guys who don't know the first thing about nutrition and don't train at all with 6 packs) you generally need to build muscle and lose body fat. The most efficient way generally (I keep saying generally because everyone is different) is to do a slow bulk (6 months +) and a slow cut and just hammer the compound lifts along with your core work.
I don't agree with everything leangains and don't actually IF myself but this is a great article and I agree with this parts especially:
For someone interested in aesthetics, which I assume most my readers are, relative strength is the single best measure of progress and the quality of your physique. Before seeing a picture of a client, I can easily get a very good idea of his or hers body composition by simply knowing three stats: weight, height and strength. Relative strength is therefore the parameter that will be used to determine reasonable rates of progress, which will then tell you whether you might be suffering of ****arounditis or not.http://www.leangains.com/2011/09/****arounditis.htmlWant to look like Tyler Durden? Then you need to build up some modest amount of muscle and then you need to lose fat, period. The muscle is best built with heavy weight training, not 15-25-rep set flyes followed by an hour in the pec deck machine. Your gut is best lost with a good diet, not "fat burning workouts"/tons of cardio/pump'n'tone crapola. All those will do is leave you under-muscled, weak and with a severe case of ****arounditis.
It's a solid article. I disagree with his outlook on training core but for different reasons. I think training the core is a tool to increase the compound lifts and there is no reason to ignore it.
Also to your last point about failing isn't the programs fault. I agree to an extent. You will get results with any program if you eat right and put the work in. However some programs are less efficient than others. I can't agree that a program that ignores heavy deadlifts and squats is an efficient program for a variety of goals.
*Not bashing p90x or Insanity I hate people who do that, there is nothing wrong with either bust your *** and get results*