We made a mistake when we booked a Viva Air-flight from Cusco to Lima. The scheduled departure time changed more than 4 times before departure date and once we arrived to the airport in Cusco they told us that Checking in ar counter would cost 14€ per person. We had no other option so we paid. The only reason why we tried to check in at the counter was that online checking in did just not work. We also found out later that even online check-in has a cost. What kind of airline has check in that costs. We were lucky that our flight was not cancelled as many other fellow passengers told us that their flight from day before was cancelled and they had to fly one day later as Viva Air has like one flight a day from Cusco to Lima. Also the flight was 1 hour late, but it didn't feel like much after talking with passengers who had missed their other flights back home because of Viva Air delays and cancellations. I've been flying with over 30 different airlines and I sincerely have to say this one was definately the worst of all.
When we booked the flights there were also many other company options like Latam and Avianca. The funny thing is that Viva Air was no cheaper than those other companies. I haven't tried companies such as Avianca and Latam, but I haven't heard anything bad about them. All in all: Whatever you do, do not take Viva Air flights!