I love long exposure night shots like this, and you captured the Seattle downtown very nicely.
The point where you took this photo is top notch. You have an excellent view of the skyline where it is centered and close enough that buildings don't seem too out of reach. The way the highway takes you into the photo is a very nice touch that guides viewers' eyes and keeps them glued on the photo.
The long exposure turned out nice with some of the streaking lights of cars and street lights.This truly is a nice, clear photo.
Here are a couple of things I would think about: In night shots like this, you want to contrast the lights of the city against the dark backdrop as much as possible. The way it looks now, you background is just a few shades too light. The low clouds are too visible and your sky looks more dark navy than black. To add more intrigue you'd probably want to desaturate the sky and make it as black as possible.
In terms of framing, it did a fine job. I might mention though that the far left side of the photo seems a little off since there aren't any tall buildings there. It allows the lights of the city to trail back and distract my eyes from the more beautiful skyscrapers. If there was any way to shift or center it differently, that may be something to consider. But, since the road placement is perfect as it is, that change may not be possible.
Overall, this is an excellent photo. Can't wait for more!