Wow, it's an area that we're probably going to hit up big time in the Spring so I did a little looking up info.
At first blush it looks like the answer to your question is that it's a good road but the last part is well maintained gravel.
But read Trip Advisor reviews.
Beautiful park but the staff and enforcement of rules.
It's one thing to read an occasional disgruntled report on a situation but when you get several saying the same thing I tend to start believing them. Don't need to butt heads with someone on a power trip.