The general visitor experience of this remote site has already been well-described by the previous reviewers, but I’d like to add information about what it is like to go there with your own (rental) car.
The site has no less than 4 entrance roads, of which 2 are officially recommended. They lie along the RN40, the seemingly endless road that crosses South America from North to South. The first access is 88km south of the town of Perito Moreno. Here you have to turn into a 27km long gravel road with several steep sections. It seems that the tours always take this access. Online it is stated that most cars can make it, except for those with trailers or heavy loads. However, I saw a handpainted ‘Solo 4x4’ sign when I drove by. So with a regular car, this way of access should not be your first choice.
Instead, drive on for another 32 km on the RN40 in the direction of the town of Bajo Caracoles. Here you will find another access road, it is signposted with a Cueva de las Manos sign and indicated on maps as RP97. This is a wide and well-maintained gravel road, 47km long, that only ascends and descends gradually. You’ll easily drive 50km/h here (the speed limit even is 80!). I saw a YouTube video of a couple driving it on a motorbike and it immediately boosted my confidence that I could manage too in my rental car. And so I did.
Along the way, you’ll encounter many guanacos, especially on or around the RN40. They blend in well with the landscape so sometimes I was surprised by their sudden appearance. They tend to scare away from cars and generally aren’t so dumb as to cross the road at the last minute.
On a final note, the entrance fee nowadays (February 2024) is 12,000 pesos. This is the same amount in USD (12) as reported by Jarek in 2014.