http://www.eurogamer.net/articles/digitalfoundry-2017-horizon-zero-dawn-ps4-pro-performance-analysis
The subtitle they used on Twitter is "Horizon Zero Dawn is PS4 Pro's best 4K presentation yet."
Update: Digital Foundry video:
https://www.youtube.com/watch?v=qTH8OnQKWeY
Horizon's excellent performance at checkerboard 4K vs the native 1080p of the base PS4 version is a great achievement. While the Pro hardware has 2.3x the GPU power of the standard model, memory bandwidth hasn't scaled in step - and it's rare that we see a PS4 engine scale so gracefully between 1080p on base hardware and 4K on Pro (checkerboard or otherwise). That Guerrilla has achieved this with no impact to performance is impressive enough, but the team has pushed the envelope here, handing in more visual enhancements over the base version of the game.
While Horizon would be lauded for its resolution boost alone, what we like about the title's presentation is that Guerrilla has accepted that it's not just the pixel-count alone that matters - more is required to deliver a great 4K presentation. With that in mind, we were really happy to see improvements to resolution on some textures. Also worthy of praise is a marked increase in texture filtering quality. Lower levels of anisotropic filtering on base hardware can stand out on a 1080p image - but the effect is much more pronounced at 4K. Thankfully this is not an issue with Horizon.
The subtitle they used on Twitter is "Horizon Zero Dawn is PS4 Pro's best 4K presentation yet."
Update: Digital Foundry video:
https://www.youtube.com/watch?v=qTH8OnQKWeY