Cheap pricing, very upfront about their fees for choosing seats/checking luggage egc. The fare was extremely reasonable ($30/person) to fly from Cuzco to Lima. $97 total for 2 people with 2 bags each plus choosing our seats.
I will say beware the situation if you're flying from Cuzco airport as apparently Sky does not have any sort of dedicated gates. On check-in our tickets listed one gate but when we arrived it was an Avianca flight and we had to do a bit of a scramble to find the correct gate.
Seats did not recline and that could be an issue on a longer flight. Drinks/food/snacks are all for purchase at fairly standard (slightly inflated) airline prices. Cabin crew was fine, nothing bad or remarkably good.