I didn't think much of that Paris Hilton episode. For that matter, I don't think too much of this entire series so far. I did enjoy the Lemmiwinks saga reprisal at the end, and all episodes have had their moments where I've laughed / chuckled, but for the most part, I feel South Park could maybe have been put to rest before this series.
Favourite moment from this series (that I can remember): The episode where the Wallmarts are taking over South Park. Everytime someone dies, they shat themselves!