Many road construction delays (but not very long) near the turn-off for the visitor center, and some gravel stretches, from Hilo side. Road still nasty from west (Mamalohoa, or Belt) side, just go slowly. Center has some telescopes to look through, a nice view, but I wouldn't bother again (but I suppose worth a visit? Pretty feeble wall display inside about glacial "morrains" instead of "moraines" and a little gift shop). However, be sure to use lower gear on the way back down the road; it's pretty steep. (imagine the road to the very top is something else!)