Conclusion

When looking at the performance offered by the Catalyst 12.8 WHQL one can see that it is much like the performance of the Catalyst 12.7 Beta from june 25. While in almost all game the difference in performance was around 1 % at max we noticed three main issues. First of all Batman Arkham City was freezing when loading at the nVidia logo... (Pretty sure it was done on purpose then). Tried to launch the game once, twice, three time, same! the game stays stuck at the nVidia's logo, can't even get to the menu. We managed to fix that by doing alt-tab just after running the game so it loads while we are on the desktop then switch back to the game.
Then we noticed a huge drop in performance under Dragon Age II going from an average of 50 fps with the Catalyst 12.7 to 37 fps with the Catalyst 12.8 WHQL. A performance glitch we experienced already with the Catalyst 12.x Beta from june 12 that wasn't present in all other drivers we tested.
The third issue is related to the power consumption that me measured higher than ever. With previous drivers we had a power consumption in idle that was around 65 Watts, here we got 70 Watts. One would say 5 Watts is nothing, well under load (furmark) we had 20 Watts more than before with 270 Watts measured vs 250 Watts in the past. Still nothing?

In the end the Catalyst 12.8 WHQL aren't the best drivers we tested due to those issues, they may fix some other issues and improve some performance in games we didn't test so we can't not recommand them but if you are a Dragon Age II player then you can stay without hesitating with the Catalyst 12.7 Beta.Unofficial Beta from june 4.