Eurogamer has dug deep into PlayStation 4 Pro performance, and found a few flaws. While the vast majority of "PS4 Pro Enhanced" games run fine at higher resolutions (up to 4K), or with more advanced anti-aliasing and with other graphical enhancements (if you're using a 1080p TV), a few games have been falling short of the regular PS4's frame rate. Notably, Skyrim and The Last of Us have both been demonstrated falling a few frames short of their target frame rates (30fps and 60fps, respectively) when running at 1080p. Eurogamer also founded mixed results with Deus Ex: Mankind Divided, with some scenes showing worse frame rates and others showing better frame rates on the Pro than the regular PS4.
Obviously, for most gamers, graphical enhancements are typically a secondary priority after a stable frame rate. According to Eurogamer, Sony's own developer standards state that PS4 Pro frame rates should be “meet or exceed” that of the PS4. Sony has responded to Eurogamer's claims, stating: "We are aware of the issue and currently investigating." So hopefully these games can be fixed soon and PS4 Pro buyers can get what they paid for across all titles.