Not really. The Cessna had no parachute, and the statistics seem to imply that most pilots ditch successfully. See e.g. http://www.equipped.org/ditchingmyths.htm
If anything, it's surviving in the water that is difficult, especially in cold waters.
If anything, it's surviving in the water that is difficult, especially in cold waters.
As long as you're wearing a shoulder harness, the main risk is drowning after the ditching. To have a good chance of surviving, you need to be already wearing a lifevest, know how to open the door underwater by memory, and then be able to get out. You can do an underwater egress course, which helps increase the odds.
(The link supplied by @lutorm contained some stats.)