San Diego will always have a special place in my heart. I lived there for 10 years, 5 in college, and 5 years working, and there is still much I haven't seen and done. That is what makes this place recreation/vacation central. Living in San Diego long term, however, is not the same as vacationing there.
First of all, I spent 9 years and 3 months living with roommates. Despite having a full time job that paid the national median salary, and despite having full benefits, there was no way I could afford the rental prices without a roommate. And roommates come and go. I don't know if they're flaky everywhere, but there seems to be a surplus of them here. Also, sometimes landlords put the place up for sale. In 2005 condo conversions were all the rage (which I suspect contributed to housing bubble). As students, my roommates and I were forced to move so that our crummy condo could be renovated (half-ass) and sold for half a million. On average, I had to move every year and a half. And each of those times I felt falsely optimistic about finding my own affordable studio. I have nightmare stories about the over-priced, mold infested, closet-sized apartments I've seen for rent. When I finally did find a suitable place, for $825 a month, lo and behold the landlord put it up for sale 9 months later. *sigh* ...
San Diego is a beautiful city with much to offer. And the natives (10 years or more, not the transplants) are very nice people. There are very distinct neighborhoods with different flavors. BUT it's the finest city because it's one of the most affluent. After some serious budgeting and asking friends that taboo "how much do you make?" question, I've ascertained that a single person needs to make about 50k to live alone, with some leg space, in SD. Otherwise, your savings will drain slowly, no matter how much of tightwad you are, as mine did. I had no other choice but to move back home with my parents, or live in a 11x10 bedroom with 3 other roommates.
San Diego: Beautiful, great weather, diverse, hip, sophisticated, fun -- but also terribly elite, libertarian, crowded, expensive, bad public transport, and a steadily shrinking middle class.