We don't think so...unless you cannot figure out what D, R, N, and B mean.
Operating the ESS takes common sense.
Obviously, the driver will push buttons instead of using the gear shift lever. We think that the ESS is actually EASIER to use than the factory shift lever but that is purely subjective. Many valet drivers in Las Vegas complimented our test car and noted that Toyota should have done this in the first place. (^^)
The only time when we felt we needed to get used to the ESS was when REVERSING. We had a tendency to sweep our hand across in search of the shift lever when gong BACK INTO DRIVE. No more sweep, just push the button.
In the end, vehicle safety is all up to the driver and common sense. There are over 10,000 units all over the world and everyone seems to be doing just fine.
If the button is not for you, we suggest re-installing the factory shift lever.
However, Prius owners are smart and we believe that you should have no problem with the unit (^^)