I love the series, despite its minuses (I successfully ignore them:)
The city is living and breathing, but only difference compared to Yakuza 3 is access to rooftops and underground - its up to you to decide if its bad. I felt like returning home.
Fights and mechanic is satisfying, fighting is little bit different with each of them, but the base is still the same. Compared to its predecessor its now very easy (Amon got me 3 times, 1 in arena when my partner died at the beginning of the fight otherwise I almost didn't have to use healing).
The amount of mini-games is awesome, I kept returning to them a lot (pachinko was not so much fun, and mahjong with chess were hard to learn).
Each character has its own story and personality.
What disappointed me was the localization. Everything looked like Japan, but people did talk like in US ("urusai" apparently means "shut the **** up you idiot" ....ehm... really?)
Well... despite that i really love this game. Its up to you what you will think:)