This is probably the coolest place I've ever camped at. We stayed at the group camp site, which I highly reccomend because it's off to the site instead of piled on top of one another, like the individual sites. Just down the road, about 5 minutes, are the hot springs and the Rio Grande which are INCREDIBLE. Highly reccomend taking a dip at night before bed - super refreshing and the stars are spectacular. Santa Elena Canyon is across the park a ways but it's absolutely 150% worth going. This whole place is stunning.
We camped here over New Years. It got down to 10°, which was crazy cold. This park is a dark sky park, but it was overcast while we were here, so I haven't seen that part of it, yet. The rangers and camp hosts were all very sweet. Bring a mallet and as thick of a mattress or pad as you can find - the campsites are rocky and the ground is very hard.