While visiting Yosemite we stayed at the Mariposa KOA, which is actually in Midpines. Mariposa is a cute little tourist town six miles down the road. Midpines has a gas station and a post office. KOA likes to affiliate with the tourist areas.
There is no, none, not any Verizon voice service in the park. Apparently it is between two cell towers. Oddly enough we had Verizon 4G service. It was generally good enough, except for one night when it dropped completely. We were able to get satellite, but I wouldn't count on it. Interior roads were very narrow asphalt, sites were gravel. There are picnic tables at the sites. Our neighbor ran in to his when parking. No data on restrooms. Power was good, water pressure was good.
How you feel about this park will depend on what you are driving and what tow bar you are using. You enter the park and go up a steep hill. There is a circular area at the top, where you stop to register. See the yellow sign on the tree mid-photo? It says go to the right of the tree. If you are 40 feet or more and towing AND you have a Blue Ox tow bar, don't do it. You may or may not get around the loop, if you don't your tow bar will be completely bound up. Go straight into the circle, unhook, and then do a two point turn to reverse your direction of travel.
After registering, you go back down the steep hill toward your site.
The park was full of rental RVs. Each night was a convention of Road Bears and Cruise Americas. IMHO many of the drivers were going way too fast for conditions. It was somewhat nerve wracking to have someone backing in to their site across from us, and someone else scooting in between our pickup truck and the backing guy.
The good thing I can say about this KOA is that they do not allow camp fires.
If we return to Yosemite, I think we would try somewhere else.