>>296407470
RMAs were pretty flaky in the beginning. Not as bad as HTC, but Valve didn't anticipate their shit to break down after a month, which it does. They figured it out now, so at least RMAs are less of a pain.
As for hardware. Generally each component has flaws, lighthouses can break down for no reason, headsets' cable is the weak point so make sure you treat it well, speaker/screen issues are more rare.
Index Controllers for sure will squeak and for sure will drift if you use the thumbsticks. Other issues are more of a lemon basis, but don't be too hard on the touchpad and grip. For some people trigger gives out earlier than thumbstick. Expect stuff like touch sensors to go haywire or unexpectedly stop working in buttons/thumbstick. Generally if you don't want to RMA, don't ever go Valve.