This is probably my favorite road on Earth to drive - especially in the fall. You'll get a beautiful mix of deep green Hemlock colors and bright yellow Birch and bright red Maple foliage for landscape with rolling hills, streams and rivers nearly around every turn.
It's my belief that the 20MPH speed limit is not for safety but to ensure you don't miss out on some of the most beautiful spots in Maine and its wildlife. I've run into(not literally) so many moose, rabbit, partridge, turtles, weasels, various birds, deer and squirrel on this web of roads - it's very exciting.
There are 2 approaches that I take when driving this road. Both involve, in any weather or temperature, windows down.
1- No music, no talking, just listening to the tires on the dirt, splashing of puddles and wind or rain.
2- Banjo music - I think the Grateful Dead (Cumberland Blues) and/or Old & In The Way or other Jerry Garcia banjo favorites are quite enjoyable entering BSP. Exiting the park is much more somber, knowing it may be another year before you visit again.
If you take the drive, please be respectful of the wildlife, posted speed limits. Be mindful it is a narrow road and watch out for hikers!