I picked this up on PS4 (retail) and it's really a lot of fun. The time traveling premise fits really well with collecting a massive army. Great excuse to have endless battles. Also, now I see what people have meant when they said the crafting system was better than other Koei games.
The Gauntlet is also pretty great once you figure out WTF is going on. Though at first glance Duel Mode seems kind of boring, kind of like those forced attempts at a Vs mode in old side scrolling beat-em ups.
While the framerate doesn't stay locked at 60, it does at least run way better than Dynasty Warriors 8 on PS4 - that is a kind of trashy port, you can't even stand still and spin the camera without the framerate stuttering and hiccuping when nothing is on screen.
I do hope Samurai Warriors 4 is technically tightened up on PS4.