I think the concept of the diet is certainly a good one; low sodium (most of us eat too much already) and lots of lean protein, fresh veggies and fruit, and including whole grains in the diet. This is the basis of a good dietary approach for all of us. As a whole, however, I do not believe that DASH goes far enough.
One of the issues I have with it is the part about low fat. Not that I don't think we need to consider lowering our fat intake (many of us could do with a lot less) but rather that we need to think about the types of fats and the ratio of fat that we ingest. I do not consider margarine or other fake fats to be a good choice. Using healthy fats, as I wrote about here, in moderation is a much better choice than using trans-fats.
Another concern is that the diet does not specifically mention how increased fiber content can lower both blood pressure and cholesterol. A study published in the Journal of the American College of Nutrition showed that "bean consumers had lower systolic blood pressure in comparison to non-consumers." Beans and other high fiber foods need to be a part of everyone's diet and are a beneficial part of reducing blood pressure.
Also there is the concern that although the DASH diet does promote exercise it does not exactly look at the stress levels or other holistic concerns. Teaching people how to breathe or to engage in active relaxation techniques has been proven to help lower blood pressure. Meditation, Qi Gong, Yoga, and other mindful exercise practices also have techniques to help lower blood pressure.
Lastly, DASH does not mention or strongly promote those foods that are specifically helpful for lowering blood pressure such as garlic, onions, hibiscus, and foods that are high in magnesium or potassium. Nor does it caution against those foods that promote higher blood pressure which I wrote about here.
So overall I think that the DASH diet is a good place to start when it comes to lowering blood pressure but I think there are some other changes that can be added to the diet to improve it.