I was up there for open-gate day last weekend as well; a four-wheel-drive high-clearance vehicle would be ideal, but I saw folks making it up successfully in compact 2WD cars, too.
My evaluation is somewhat colored by the vehicle I drove: a 2007 Honda Ridgeline, which has on-demand 4WD. The dirt road between Schulman and Patriot groves was not bad, just not advisable to go faster than about 15-20 mph: washboardy in spots, occasionally dodging larger rocks in the road. 2WD taken slow should be fine IMHO. The 4 miles from the Patriot Grove to the gate was a good bit freakier and adrenalin producing, but as long as I was careful and went dead slow, I got in and back out just fine. Several spots where one and only one car can traverse the road for a few hundred feet; 2 or three washout-like spots where you have to pick your path to avoid high-centering.
Mostly, just don't be in a big hurry on this road.
Unfortunately I started showing AMS symptoms, so I didn't make the hike up to the summit; bailed out on Sunday morning.