NVIDIA's Reflex tech makes for better first person gaming because it helps reduce latency. A few games have it and today, Overwatch becomes the next game to pick up this really nice feature.
NVIDIA is touting up to 50% reduction in latency, which is a pretty good amount if this is indeed a real world result. Right now, it's only available on the Test servers, but this free update should be coming down the pipe to all soon. You'll have to sign up for the PTR via the Blizzard client to opt into the version with Reflex, but doing so will let you get the fastest response time possible should you have a NVIDIA supported card.