So they analyzed the footage and were impressed with the performance.
"A full HD trailer encoded in Apple's ProRes format grants us the opportunity to pore over the game's finer details at a quality level akin to the software running right in front of us. "
"The available evidence from this and other Sony trailers suggests that this is indeed the case, owing to the vastly higher fill-rates afforded by the PS4's powerful Radeon graphics processor. Chief among the priorities in its design is of 176GB/s memory bandwidth at its disposal in concert with a whopping 32 ROPs - stats that place these aspects of the PS4's architecture on a par with some of the fastest PC rendering hardware."
The GPU was also well received and compared to an HD 7850 card which is capable of running even BF3 without a fuss.
"Put into perspective, this level of throughput exceeds that of even capable £120+ PC graphics cards, including current mid-range favourite the Radeon HD 7850. Recent benchmarks of this card show little issue in running DirectX 11 titles like Battlefield 3 on high settings at 1080p60. In other words, given the right optimisation for the new version of Sony's custom LibGCM graphics library, there's more than enough of an overhead for the PS4 to push for more than what we're seeing here - or at least break even with 1080p going forward."
It displayed a lot of effects and ran at a perfect 1080p 30fps.
"It's a beautiful game overall, but with compromises that only make sense if frame-rate has become the priority. Those hoping to see a trend of fluid 60FPS titles begin from day one will be disappointed, but for Shadow Fall the emphasis is placed on a cinematic spectacle rendered at 1080p30. The frame-rate is confirmed to be capped at 30FPS during interviews with the studio, and based on our feed we see this is absolutely 100 per cent stable throughout the entire demo."
The video stream was capped at 30fps so they thought it could be a reason why Guerrilla kept the frame rate down but feel that it's more likely that it's just going to be capped at that frame rate because that's all it can do with those given visual effects.
"No drops, no screen tearing - it's a smooth play-through all the way, suggesting that the frame-rate could be running higher if it weren't locked down on this figure."
They are thinking that the PS4 will have enough overhead to make a new 1080p standard but the 30fps standard might (probably) won't be broken. That being said, they did know that this demo was made on older developer kits that have since been updated so based on that and specs alone, they know that PS4 has a lot more power under the hood.
"Based on specs alone, the PS4 clearly has far more to offer than what we're seeing, and it's worth remembering that Guerrilla would have developed a large chunk of Shadow Fall on incomplete hardware. Our understanding is that final kits based on actual PS4 production hardware are a relatively recent phenomenon, and now the developer has a fixed target to aim for, we may well see significant engine improvements. But if this stands as the level of technical quality we should expect for Shadow Fall's final release, we'll be due for one of the most technically compelling launch titles we've seen in a very long time."
http://www.eurogamer.net/articles/digitalfoundry-killzone-shadow-fall-demo-tech-analysis