I've removed directions due to too many people disrespecting this spot. Sorry!
Personal Experience: In my opinion, and especially for San Diego, this is a legitimate waterfall. The scores of graffiti adds an interesting, urban touch which is sad (not only because the graffiti is pretty terrible) but also colorful and slightly surreal. I guess that's what happens when a waterfall is easily accessible and neighbors a college town.
This is one of the only non-seasonal waterfalls in San Diego. Alvarado Creek draws its water from much of Del Cerro, San Carlos,
Fletcher Hills, Grossmont and some of the hilly areas south of the I-8
corridor from Grossmont west until Fairmount Ave. Here's a great site to learn more about the waterfall.