i did the entire route from hanoi to saigon, much of it on the main highway.
it was not enjoyable. way too much traffic, and the constant air horns will
drive you insane. the section hoi an danang and over the pass was nice, tho.
as i flew out of hanoi, i promised myself i'd nevernevernever return to vietnam.

i'll be back this summer, but will do hcmc-hanoi by train. riding will be in
the south from cambodia, and in the north thru the hills to china.