There are mild elevation changes. There have been complaints about the exhaust fumes and dust from the adjacent freeways. These complaints are largely exaggerated. There is a steady up river breeze that dissipates exhaust fumes and dust is seldom any problem at all. The steady up river wind surprisingly results in uphill runs well faster than downhill runs.
Lighting is excellent at night.
It is swept regularly. Bike, blader, runner and walker traffic is steady but never congested. Peter Wright I've ridden the LA River path and am very disappointed in it. Particularly its location. Riding into the face of oncoming freeway traffic is not my idea of a good time.