I moved here from a place in Colorado with 300 days of sunshine a year. Everyone said, upon hearing I was moving "You know it rains a lot there?". Buy a jacket. Go outside when it's nice, don't when it's not. Living your life by the weather is pretty silly.
I have been on 100% travel in the US for the last year, and the three weeks I spent in Oregon were very depressing. It literally rained every single day; the longest period without rain was about 6 hours, or the couple of days it snowed. I would never want to live there for that reason, I was happy to leave.
As for Portland itself, a friend told me to watch the show Portlandia before I went. At first, I thought the show was way too over the top to be funny. After actually spending some time there, it became apparent that if it was any less over the top, it would be a documentary.
On the plus side, Oregon is very nice. Crater Lake is spectacular in the winter, and perhaps the most beautiful area in the US. There are also many awesome Art Deco bridges along the coast.
I should also note that this summer has been absolutely magisterial.