When we purchased in early 2004 we looked all over Temecula and even had some $$ down at a place up there. To echo the comments on here, I really liked the areas in the city itself, and especially to the south near 79. Better commute to San Diego, and far away from the northern traffic. We also lived there in an apt. off of Margarita 5 years ago and liked it quite a bit, but it sure was hot in the summer!
In 2004 we ended up buying in San Marcos because prices were not that much higher. 495k for 3000sqft. home in San Marcos vs. 450k for the same one with same yard in Temecula. Beofre buying up there I would seriously look at some areas of San Marcos again. Santa Fe Hills in San Marcos is one area where prices might still be comparable to some areas of Temecula. Even my old neighborhood of Silvercrest in San Marcos a 2700 sqft. home sold for the mid to high 500s this year. IMO Temecula gets buyers with $$ and good jobs from the OC and LA, wheras San Marcos does not, and that may explain the pricing.