A lot of people have really strong criticism of Kiwami, that I can't really confirm or deny. I haven't played the original Yakuza (or Yakuza 2 for that matter), so I can only view Kiwami within it's own context.

It's fine! I like Kiryu, I like how he feels to play. I enjoyed the story well enough. It just didn't wow me like 0 did, and I felt the unique systems for Kiwami (Majima everywhere, Kiwami actions) were really annoying.