With that out of the way, Gungrave is an interesting anime that has a lot of strengths, but also a few weaknesses. This is because it has got two components to it:
1) A very watertight character-driven gangster story that takes up most of the anime, which is very much worth the price of admission.
2) While it's not quite correct to call it this, there is a point where I would describe the show as devolving into a Monster of the Week format involving fantastical elements that is unfortunately rather mediocre. However, as I say, this latter part is a minority of the anime's runtime, and the ending few episodes really brings the show back to what it does best.
The writing and characters are excellent, the art style is a bit weird at times but still perfectly serviceable, the music works really well at creating the right mood for this style of story, and the action scenes are generally good*.
A few other (non-spoiler) details...
The show spans a period of 30-40 years, showing the growth of various characters throughout their lives (but focusing in on the relationship between two in particular). It handles characters aging very well in the main, with the exception of Harry becoming a bit of a chain smoker and aging an extra 20 years more than he really should at the end.
*The show handles fight choreography for the mundane gangster shootouts very well, and there are also a couple of the boss fights with fantastical elements that are reasonably decent as well. However, the fights with Necrolyzed enemies and Orgmen in particular that happen later on (you'll know them when you see them) are very clumsy and underwhelming, with the wrong kind of low-detail sluggish bullet spongey combat. You'll just have to grit your teeth and bear them, but as I say, most combats aren't like that.
The mafia is also slightly more messy and OTT than they are in real life, but one can forgive the anime for that because it is in the show for the sake of adding in more action and drama.
Lastly, the idea of turning some characters you know from earlier in the anime into monsters of the week could have been a really great twist on the story formula, but it isn't handled to its fullest potential.
Even though it's relatively old at this point, Gungrave is one of the better shows that you can watch, and is an excellent gangster anime.
And while I have given it a 7, I don't hand out high scores lightly, so don't let that fool you. I'm not some clapping seal that ignores the lower half of the ratings system, and while I do enjoy some trashy anime now and then, this isn't one of them. It's really solid and worth a watch.
