Great bike ride. The path is relatively smooth and goes under all of the roads and highways. If you want to do a little extra, take a left when you reach the end and loop back through Coyote hills. There is about a mile along the sliver of land that takes you back to Coyote Hills that is rocky, so don't take that path if your tires aren't cut out for it.
Overall, a very nice ride. I parked at Isherwood Way, near Paseo Padre Pkwy. Once I parked, I noticed there are two trails along the creek. The inner trail is gravel and dirt. The outer trail is paved. I took the paved trail towards Niles Canyon. Very nice ride and pretty views. It was about 6 miles there and back to the parking lot, so I went the opposite way. Going that way was not as scenic, and had more people, but still a decent ride. Throughout the ride, I noticed several patch up work on the paved trail, so the ride wasn't very smooth. Flat ride, with the exceptions of going under the bridges, in which case you have a minor hill.
Will probably go again soon. It is good training trail for an upcoming race.