After having read all the negative reviews, I booked a JetSmart flight from Montevideo to Santiago de Chile. I left for the airport with very low expectations (even taking extra food). Very much to my relief online checkin, going through security and immigration and boarding went very smoothly. The flight was 15 minutes late, but arrived in Santiago almost on schedule.
Pleasant, the pilot warned for turbulence well in advance when flying over the Andes. He evaded the bad weather and landing at Santiags was perfect.