I found the road to Hana to be long. While gorgeous, it is a long haul when you turn around and go back. We took the back road to return (in a minivan, no less) and didn't find it to be difficult or dangerous (a few tight turns, some unpaved sections, potholes). Actually, it is peaceful and quite sedate in sections, and the views are unreal (especially the views of Molokini crater). Add in the significant time savings and fairly linear drive back, and it was one of the highlights of our trip. really, if you aren't in a hurry, it is a nice, slow drive.
We heard rumours in Maui that the road had a bad reputation that was "created"--the landowners alongside it value their privacy, and would rather the hordes going to Hana went back to the resorts the way they came, as opposed to driving on the south shore.
With the road closed, this isn't an option, but if the road opens back up, i'd highly recommend considering it.
Edited to add: According to this website
http://www.hawaii-guide.com/index.ph...opens_on_maui/ the road is now open again! Can anyone confirm this?