A new replacement highway was built over a decade ago and it handles all the bus/truck and vehicular traffic that made the original road so dangerous. The original "Death Road" is a tourist attraction now, probably the most popular/famous spot in Bolivia after the Salt Flats.
One section is certainly spectacular with sheer drops and no guard rails in parts, and the only danger lies in losing concentration or being a complete idiot due to over confidence and smokin' a corner too fast, but even that is kept well under control by the guide strictly controlling each tour group.
In all honestly anyone can go down it now with zero issues whatsoever. There are dozens of bike/tour companies offering the ride to tens upon thousands of tourists every year. If you're an experienced mountain biker then I think you will, quite frankly, be bored if for no other reason the group tours stop continuously for photos.
The photo opps are really cool though.