Over the last few weeks I've been playing through Yakuza 3, 4 and Dead Souls (repeatedly), starting with Y3. I think I can agree with some/many that Y4 is the 'best' and DS the worst from these three.
Y4 offers improvements over Y3 in terms of game play/controls as well as more diversity with more playable characters, although it's debatable how fun some of them are to play or story-wise. On the other hand I'm glad I started with Y3, because I can imagine going back to Y3 after playing Y4 could be frustrating. I'm realizing that now, after convincing myself to seriously attempt Platinum for both..
One of the things I very much appreciated about the series is the general lack of vehicle game play, although I hated the sections that featured it the absolute most. Mandatory driving, or racing in open world/city games is not something I enjoy, Sleeping Dogs (and ****_Dogs) reminded me of that.
So, Dead Souls. I had read it was bad, that usually makes me curious to find out how bad or what people mean by that. Haha. At first I kind of enjoyed the different combat mechanics along with the familiar setting and characters, or so I thought. It just gets very tedious and by the third character/chapter I had really started to feel regret, especially on Dead Souls difficulty. Oh, and Dead Souls difficulty is ridiculous. Not impossible, just BS and even more tedious. The much hated QTE's aren't so bad though, once you know how to 'cheese' them, but not quite Knight's Contract level of frustrating.
In summary, I enjoyed most of my time with the (western released PS3) series, but I fear I may have burnt myself (out) a bit by playing through them repeatedly over the last weeks, playing through DS three times in particular. I have 'only' a few trophies (mini-games and Ultimate Challenges, lol) to clean up for either, so I imagine I keep working on those when I'm feeling the heat.