As a Seattle resident and frequent visitor to Fremont and the Troll, I can say that all the local color was quite authentic. I've never actually seen the troll get up and move around, but it wouldn't surprise me all that much.
By and large, yes, it was (he even got the PPC right). However ....
<nitpick>
Fremont Ave. is *west* of the Troll, not east.
The only thing you can buy down at the ferry dock are tacky t-shirts. No fisherman's wives to be found.
No sane person would stroll under the Viaduct at night. Nor can you just walk there from Queen Anne.
It's REALLY hard to avoid Fremont if you're coming from Queen Anne and going to the University. Not impossible, but very very out of the way.
Gasworks Park never takes an article (i.e., it's never The Gasworks Park)
I've never heard an outsider describe our atmosphere as "terminally friendly". We're polite, yes, but.... there's a thing much debated here called "the Seattle freeze" that supposedly makes it almost impossible to make friends here. I suspect Seattleites (most descended from already reserved Scandinavian and Asian cultures) look askance and wary at aggressive attempts at friend-making. Plus there are a lot of engineers.
</nitpick>
Not that the last bit would have changed the story at all. And I did like the story. Even after it took a turn to Pure Evil.
(trying to catch up, really I am)