The wife and I just rode it a few weeks ago. South bound the worst part as has been for at least the last 30 years is the climb from Pacifica up to the slide. Then the slide itself going south is fast, the road is bad and some places there's a shoulder and others there's not. There are lots of cars all the time. The further south you get on the slide the better everything gets.
So, I think that overall riding the tunnels will be safer than the old way with cars. But the most dangerous part, the climb out of Pacfica is unchanged.
I understand the old road is closed to all traffic now and won't be open to peds. and bikes for about a year. Even when it does open the first time the roadway falls into the sea I can't imagine they will fix it for bikes. They will just put a fence up at that spot and call it good.
who ever thought building a road here was a good idea anyway?