Yes, this actually starts in Hillsboro, at the end of the Max line.
I have ridden this in some capacity in both directions, it’s great either way. Nice and gradual ascent if coming home from a coast trip, or a wonderfully long descent going out to the coast (after a somewhat brutal climb in the morning).
There is a (very) brief stint of gravel, couple of miles. Very easy riding. Great for hot weather, as the ride is very shady.
If you start out this way, I would stop for breakfast at Maggie’s Buns in Forest Grove and buy the buns! It will last you the entire trip.