According to Game Watch (via DualShockers), Yakuza producer Toshihiro Nagoshi told the press at the Taipei Game Show that the PlayStation 4's architecture caused a bit of a headache during the development process, but it's nearly ten times more powerful than the PlayStation 3:
"Comparing the PS4 to the PS3, performance is almost ten times higher. There’s a big difference in graphics and effects are also beautiful. Battles in particular have become smoother."
Comparatively, the PS3 version of the upcoming Yakuza: Ishin will see great improvements over Yakuza 5, especially in the gameplay department. In addition to smoother combat, it's already been confirmed that the PS4 version will run at 60 fps and in 1080p resolution.
Yakuza: Ishin is scheduled to release exclusively in Japan for PS3 and PS4 on February 22. There's been no word on western localization.