tcg144 - mostly depends on what you are looking for.
The DP provides plenty of power and quick throttle response and generally works fine. The F5 tuner switch makes it easy nice to be able to switch between tunes on the fly with a push of a button.
As with any tune one has to be very aware of the EGT's (EGT gauge is highly recommended). The DP will spool up and under high gear, high load the EGT's will climb past 1300 F (measured at the #8 position of the exhaust manifold). The solution to that is to downshift and ease up a bit to hold the EGT's at or below 1300. The DP will also roll some black smoke under heavy throttle, as in near floored. The boost will climb over 20 lbs vs the 12 to 15 lbs in stock mode. In short the stock PCM program is being modified and certain constraints are being removed to allow the additional power to be generated via more fuel and other parameters being modded. For passing and climbing the hills, it was a nice to have the additional power and response. It was also nice to have the much improved throttle response of the line or at slow speeds.
There are some of us who have experienced a mild surging in our rigs around 45 to 50 mph at light throttle. Jody at DP felt the surging was an injector issue. It may or may not be. Not everyone with 7.3 vans is experiencing the surging and many people are very happy with the DP tunes, and the mild surging I experienced was in a narrow speed band under light load cruising conditions and not present outside of the that range.
I ran this for about three years and over 20k miles and I was okay with the tuner. What was less satisfying for my type of driving was the smoke and higher EGT's under heavy acceleration and load, and the mild surge at 45-50 (33's w 3.73 gearing and a built out 4x4 van). The smoke and EGT's required my being careful with throttle on the hills. The surging required not staying in that speed range under cruise conditions or switching out of the tune which can be done on the fly.
Happy to answer any other questions.