PowerColor's HD 5770 PCS++ is an excellent addition to the HD 5770 market. It is the only HD 5770 that comes with a Volterra voltage regulator which allows dynamic software voltage control. While this might not be of great importance for most normal users, it is a key feature for die-hard overclockers who want to squeeze the last bit of performance out of their cards. Increased GPU voltage directly corresponds to increased overclocks, which is essentially free performance. On the other hand a higher voltage results in increased power draw which increases GPU temperature. Given the low heat output of the HD 5770 GPU and the low temperatures at default settings I am confident that the Powercolor PCS++ HD 5770 can handle voltage increases very well.
However, as soon as you ignore the additional possibilities of the Volterra voltage regulator, you will quickly realize that the PCS++ is only a minor step up from the PCS+: core clock has remained the same, memory clock is increased by only 25 MHz, the cooling solution and looks of the card are the same. But then, the price increase is only $10.
In my opinion the bottom line is that if you are an overclocker the PCS++ is a great choice, all other users could go for the normal PCS+ and save $10.