This is the most obvious challenge FSR faces - the existing solutions on the market aren't perfect, but they're delivering fewer issues than FSR does while the performance wins are comparable. FSR costs nearly the same as TAAU in Unreal Engine 4 and I can't help but think the Epic's solution produces a better result.
Ultimately, I feel that FSR is most useful at 4K in its ultra quality mode, but its utility drops off fast at resolutions and quality modes lower than that. Conceptually, I also think FSR has a less competitive position in the market of image enhancement technology. If a game only offers basic upscaling, FSR will do a better job, but why would a game only have basic upscaling? Every major engine on the market - whether it's from Ubisoft, Epic, Capcom or Square-Enix - has some form of TAA upscaling already. And because they're accumulating and reconstructing from more available data, they deliver improved results up against a single-frame spatial scaler. AMD has said that the technology may evolve, so we may well see new and improved techniques - but the bottom line is this: right now, there is absolutely no doubt that FSR can deliver stratospheric performance wins, but the higher the gain, the higher the pain in terms of image quality compromises.
