The USC vs. UCLA rivalry I think is the greatest Cross Town rivalry in the country, as both teams have had a high level of athletic excellence over the years. I have now gone to 23 USC-UCLA games in a row and have seen both the ups and the downs.
The biggest 'downer' for me of late though has been the deterioration of the USC fan's in terms of language and abusive comments directed at UCLA fans. Years ago it was predominantly the bruin fans that had lowered themselves to vicious and 'pornographic' type of attacks against USC.
Now, both sides seem about equal in their viciousness. I attribute much of these types of attacks though at those who have jumped on the USC bandwagon in the last few years.