Hole in the Rock Road is THE road in Escalante needed to access the majority of adventures. I have such a love/hate relationship with this road. 1. Its the access to some of the greatest hikes in Utah, but 2. You will leave wanting to punch the air because the washboards are so bad. The fastest we've been able to drive when the road is good is 40 mph, but an average 25-30 mph is more common.
My Subaru has had two flat ties ever and BOTH have been a result of this road after it was grated lol Make sure if you're driving this way you have a spare tire.
4wd is NOT required for this road even at the roughest. What makes this road rough are the washboards. NOW, some of the off roads (forty mile ridge + Harris Wash) do require high clearance and 4wd.
I would NOT plan on having service on this road. I have AT&T and typically lose service about three miles into the drive. I do randomly get 1 bar here and there but it is not reliable. There is also a TON of dispersed camping down this road and super helpful if you plan to get an early start for hikes that are further down the road (Neon Canyon, Coyote Gulch, Reflection Canyon)