The tl;dr: next time I'm in Portland, I'll see if I can stay at Blaine's place before looking elsewhere!
Blaine's spot is in a nice residential neighborhood east of the river in Portland. A short walk to a few main drags, this is a great jumping off point to explore the city! I would recommend a car, but if you don't have one, there are at least a handful of transportation options nearby (e.g. bus, scooters, bikes). Plus, you can easily walk to Hawthorne, a main East Side drag.
The space it self is really nice for two. It's totally self-contained with a separate entrance and is very comfortable. The bath/shower is stylish and relaxing after a day of exploring. I also worked there for 3 days, and it worked very well with fast Internet and a small desk.
Blaine and his wife are extremely attentive and responsive while we were staying. He checked in a couple times over Airbnb and answered our questions within 5 minutes. It also turns out Blaine is an amateur pizzaiolo and he made us a pie on Sunday! But amateur isn't really the way to describe it ... the pizza was superb :-) Check out @pdxdoughboy on Instagram and you'll see what I mean.
Only two things I want to point out for fellow travelers:
1) The ceilings are fairly low. I'm 6'3'' and I was fine, but my 6'7'' brother would have needed to duck to go from room to room. Won't be an issue for the vast majority of guests.
2) Blaine's son is an athlete! We could hear him playing during the day above the ceiling. It wasn't constant (maybe 15-30 minutes a day?), but could be bothersome if you're very sensitive to noise. Still, Blaine checked in with us particularly about that (without me asking, I might add) to see if it was bothering us. So this too shouldn't be an issue at all :-)
All in all, a great stay and I would certainly recommend Blaine's place to others!