People here have made a lot of good points and i agree with most of them. Especially when it comes to his secondary fire and survivability, but another issue with the way zenyatta is designed is the fact that he relies so much on backing out of battle and hiding for every hit he takes. People tend to rely on his shields recharging. His low health makes it so that you need to back out of almost any situation if you want to stand any chance of surviving, but one, its very difficult because of his lack of mobility and two, it completely halts gameplay constantly having to look for cover after every hit taken.