Tons of great ideas packed into this one, and it correctly observes how freakish the Washington Monument looks ever since they put the red blinking aircraft-avoidance lights up top, flashing like hellfire in the eyes of a hungry vampire.
A hexcrawl that is ~maybe~ a bit long relative to the encounter table that feeds it, but with solid gold on that table. Sure to leave a lot of memorable experiences for the PCs/Players.
The team gets battered by ever-shifting conditions unless they're in a "Stable" area, but "Stable" is not always the same thing as "Safe", providing the closest thing to a big Boss Fight as a logical quasi-twist. That's a nice touch, and a solid way to give "givable" stakes to the missions "ultimate" encounter.
I'd probably remake the map if I ran it, but that's my intuition against the author's intuition/playtesting, so I'm reluctant to call that "the right call". It feels like having the players have to voluntarily take on so many extra hex grids to encounter the big fight, still a minimum of 4 unexplored hexs from safety, might be too much of a rug-pull. That big fight is no joke either, >20hp, a 4d6 one-off attack, "Thorn" defensive ability, and zombie summoning. Great setup, I'd just consider moving it closer to the escape border ~or~ making victory over the 555 foot vampire stabilize the city. Or maybe have Marine One parked there so the team can fully self-extract?
There's nothing I would cut, and very little I would change or add. I think it's very close to a perfect metadimensional trip, squarely halfway between my maybe-too-simple 'CRAT : Berlin' and the wonderful 'Mandelbrot Set' in terms of complexity and length.