It’s going to build up greatly.
(disclaimer: thus far I've played Zero, Kiwami, Kiwami 2 and 6 of the Yakuza series, so those games I'm comparing this to)
It sure did. Just finished the main story, with 44/50 side cases and 37/50 friends (and 4/4 waifus, duh) completed - not 100%, but I still think I have a pretty good idea what the game is. And... it's good, very good even, but it falls short of being great for me. Which is frustrating, as the flaws are almost entirely mechanical. I'm willing to ignore shortcomings in some areas if I like the game otherwise, but this time around they just ended up being detrimental to the overall experience.
The main story sure does take its sweet time to get going, and that would be my only major criticism. Chapter 1 could use some trimming. But once the events really start to unfold, it's great. Yagami is a good new protagonist, doesn't seem like a Kiruy knockoff but a distinct person of his own (and not as awkward with women). The other characters are believable and likable and/or interesting (although some of the minor characters, especially baddies, end up being somewhat one-dimensional, but I think that's given). And the main story has a lot of a quality missing from other Yakuza games - coherence. No plot twist feels cheap or unjustified. The tone is more serious, but I'm fine with that. Zero manages to deliver a couple of emotional gut punches that still makes it the best story for me, but this is a very close second.
The side cases/friend missions are good as well, but if the main story is more serious, the side stuff should be more crazy. Sure, there are eccentric people to discover and some "why Japan, why?"-moments, but it still feels a bit tame. If an ex-Yakuza like Kiryu can attract such bizarre people, surely being a detective willing to do odd tasks for peanuts would bring out the lunatics in droves.
But then there are the added detective mechanics, and this is where the game starts to show some wrinkles. I get having them in the game, but the problem is the implementation quality ranges from "passable" (the investigations) to "tedious" (the tailing missions) to "I don't know who smoked and what" (that keyring - who thought that'd be a good idea?). And apart from those keys, which gladly need to be used only so often, the other mechanics are very frequent. Again, I get having them in the game, but the way they're implemented doesn't really add to the experience, rather subtract from it.
Most of my complaints are related to those mechanics, but then there's one other thing that really started to irk me: Keihin Gang and their continued appearance. I think they "spawn" way too frequently, but beside that, there's really no reason to go after the leaders. If you do, you'll get a couple of marbles (ok, not marbles, just can't remember what the name of the crafting material is). If you don't, you'll get a couple of passive-aggressive messages from Kim. And really, Kim is the most major issue here. I wish I could set my phone to ignore that guy, he becomes annoying really fast.
Still, it's a good game and especially a solid foundation for a new series. The mechanical issues can (and hopefully will) be sorted - if/when there's a sequel, I'll sure get it.