In the San Fernando Valley the median priced home has actually gone up. The westside has always done well with retaining value. The developers have overbuilt condos all over the city so we are seeing quite a few price reductions in the condo market.
If you are looking to buy a house and turning it around in the next year, then I would say no, it is not a good time to buy. If you are looking to buy a house and remain there for 2 or 3 years then it may very well be a good time for you to buy.