Compared to what? It's not as safe as a commercial jet or even a car, but it's much safer than skiing.
If you take a Cessna 172 on a 2 hour flight, you are much less likely to get into an accident than if you took a car on the same trip. However, if you do have an accident in the plane, it's much more likely to be fatal. If you look at the probability of death or serious injury, it's about equal.
So if you drive to a local airport for 30 minutes, take a one hour flight, then drive 30 minutes home, your chances of a serious injury on the flight are about equal to your chances of a serious injury on the drive.
That said, the injuries on the drive tend to be much more outside of your control. You can't do anything about a drunk driver that plows into you. However, in the aircraft, the risks tend to be much more within your control. For example, attempting really stupid things in the plane and flying into bad weather are among the top causes of serious injury in light single engine airplanes.
So the risk of something outside your control causing you serious injury are less in the plane.