This review is for the path that starts in Cypress Park, goes through Elysian Valley and stops in Griffith Park. It's a great ride, relatively flat and a mostly well maintained path. I ride the river several times a week and routinely see ducks, cranes and blue herons. I also see homeless people pretty regularly but have never had any altercations or problems with them.
There are several entrance/ exit points and it's fun to get off of the path and explore, especially in Griffith Park. With a little creativity, you can stretch the 7 mile River path into an easy 15-20 mile loop.
Share the path with other bikers, walkers and joggers and have fun!