I would rate this game down even further, but this actually a great starting point to get yourself into the Yakuza series. It's badass, dramatic, serious, and knows when to be funny. Yeah the skill tree is not the best, and some of the combat needs more stuff added on to it to be desired, but this is great to play nonetheless. This story doesn't affect the mainline story as much, so it's a big breather for everyone to know whether they think Yakuza is the series for them. I played this as my first Yakuza game and it was a good choice on my part.
Gameplay is eh, but what I really is the money multiplier and heat action system. Hit enemies, gain heat, and unleash devastating attacks which make you wince seeing them in the form of mini-cinematics. Doing this can drastically increase the money you offer so performing these moves as much as possible to reap yen. The money multiplier is also a great mechanic that contextually fits with the setting of 80s Japan due to the Bubble Economy of 1986 to 1991 in its country. For more money, you also have Mr. Shakedowns which are essentially super bosses that hit like trucks and take all of your money if you lose, but you have chances to take it all back from him when you defeat them.
The overworld is possibly my favorite of any video game I've played as in it's not too big, but it's not too small. You also have the option of doing side activities such as karaoke, disco, mahjong, and more. In addition, if you want to take a break from the story, Kiryu can participate in substories which are little events that happen to be hilarious always.
It's a shame though that most of these characters that are apart of the main story never get mentioned outside of this game.
Yakuza 0 is the best game in the series. It has its major problems, but I love this game to death.