We cycled it last summer, up to Eugene on the last day of the 4th of July weeked.... foolish, then back down to the coast a two weeks later. Needless to say, it was busy. There are lots of curves on the road and very little shoulder. That said, it is not much different from highway 1 through Northern California.
The trooper manning the weigh station just before Eugene will let you roll your bike onto the scale.