Batman: Hong Kong was the first DC comic book I ever read. I was about 6, so I didn't understand half of what was happening, but I've read it several times since over the course of my early teens and loved it every time. I don't know how it holds up, now that I'm old and wise, but it's high quality enough that 1/3rd of the frames are actually painted rather than drawn, and I remember it to this day. I've seen very, very few graphic novels since* that match it in the intensity and badassity of its action. Not necessarily the scale of the violence, but the back-and-forth, the visceral nature of what's happening. That's where it shines. It's also a pretty decent mystery as well. Definitely captures the Noir mood of the better Batman comics, tells a dark story, manages to work in Wuxia elements, and the art style is badass incarnate.
Aesthetically, I feel, they managed to make Batman the perfect blend of imposing and campy, so he can still have his dark glare and his shadow that blots out the moon, but he still definitely looks like a superhero. Rather than other "Intimidating" versions of batman, like the one that jabbed Joker in the eye with his 'rang and the one in Serious House on Serious Earth, this Bruce actually stands upright and isn't afraid to step out into better lighting conditions. What really does all this for the design is his cape, and the way that lighting is used to highlight it, which was probably the most fun any realism-focussed Batman artist has ever had drawing anything ever. Check it out, it's fucking amazing how they use that thing in the art. I was entranced, even as a little kid who didn't know anything about why things were designed to look a certain way.
*And I think I've read Spiderman's first run-in with Tombstone before this, (And I mean first, this was the 60's Tombstone with the green suit and the mask.) This was the one where Spiderman gets tossed around for the better part of 2 issues by a horde of gangsters, but outsmarts the elites one by one and beats the crap out of them all, forcing Tombstone to retreat when the cops show up and start mopping dudes into the baddy wagon. The action in B:HK edged that one out by a small but noticeable margin, imho.