Keep in mind that TASERs, just like any other weapon option, are things. They're not magic. They have to be thoughtfully and properly deployed in order to get the desired effect. It's not the fault of the TASER if you miss when you pull the trigger. The TASER can't do its job unless you help it to. In this regard it's just like your firearm or your baton or OC spray. The success of any weapon usage is mainly dependent upon the skill and knowledge of the operator.
Stay safe, and wear your vest! (and Buckle Up!)